There is Very Limited Space in the Star Wars Universe for this to be Viable
Contemporary western genre fiction tends towards moral ambiguity, where there are many shades of grey between good and evil. The Star Wars universe (of the movies) is a stark contrast. The heroes are basically always going to be fundamentally good and the villains are always going to be completely evil. It has to do with the influence of cheesy old sci-fi serials, 50s and early 60s television and film, and, to an extent, the influence of Joseph Campbell's (tenuously accurate) theories of how traditional myth functioned. It is a purposefully innocent and naive cosmology.
Lucas doubled down on all this in later years, to the degree of taking the extraordinary and infamous step of not allowing Han to shoot first. This is also (beyond poor writing) part of why Anakin Skywalker had such an abrupt and extreme fall to the dark side, much to the chagrin of those wanting believability and nuance in characterization. Jedi fall even more markedly into the extremes of alignment and can not endure being morally ambiguous for long.
This is all to say that, within the lore and spirit of Star Wars the Sith characters should be evil and the Light Side Jedi should by no accounts be knowingly consorting with them under normal circumstance. Even if your group doesn't care about the narrative spirit of the setting, the Force, a fundamental element to the setting, is not set up to allow for sustained ambiguity. Your PCs should be enemies and the Jedi can not indefinitely stand idly by while he commits acts of extreme evil. He can fail to act a few times out of weakness, physical restraint, etc., but he ultimately must either be a champion of light or fall to the Dark Side.
Scenarios Where it Might Work
There is some limited space for this party set up to work.
Characters generally opposed to each other can form some short term alliance for some specific goal of overriding importance to them. It is still hard to see how the Jedi can let murder-hoboing slide, but there might be some leeway for forgiveness if they are unable to act.
Were the Sith playing less randomly psychotic he could hide his evil ways from the Light Side Jedi until some sort of evil scheme came to fruition. Perhaps even as a murder-hobo he could do the murder-hobory behind the Jedi's back. The Light Side player can know as long as he plays his character as not knowing. It is presumably too late, however, for this to work. But perhaps the Sith can feign wanting to renounce his evil ways and being on a road to redemption. Jedi fall for that sort of stuff.
In terms of tamping down the murder-hobory, you can point out to the Sith that he is Sith, and while Sith may indulge in mindless slaughter in a fit of anger, to punish someone for something, or perhaps overcome by the raw evil of newfound Dark Side power, they generally spend their time scheming, bending people to their will, and seeking more power. Sith are sometimes driven by anger but crave power above all else. It is impatience to get power which is supposed to have lured them towards the easier dark path. Which is all to say that a Sith should not be killing folk for many of the classic murder-hobo reasons like "I want to rob them" (Sith care nothing for wealth) or "it amuses me" (they are a mostly humorless lot, though Palpatine has a certain joie-de-vivre). Anger, retribution, or purpose are the Sith reasons for occasional over-the-top slaughter.
Perhaps they are willing to go on an actual path to redemption. In terms of long term Star Wars character arcs they absolutely should because all Sith are destined to be defeated by good or betrayed by another Sith. They can't have a successful character indefinitely. That's the Star Wars cosmology and narrative tropes like it or lump it.
Alternatively the Light Side Jedi can be tempted by the Dark Side. You should certainly make sure the player is comfortable with this, but this is one of those rare occasions where it is perfectly reasonable for the DM to tell a player how they feel to a limited extent. The pull and temptation of the Dark Side on Jedi is a cosmic thing is Star Wars; it goes beyond flaws in character and psychology, these only determine whether they ultimately succumb. They may need to make wisdom saving throws against the pull or some such. Don't do it if it is outside the player's comfort zone (it's a game, they have to have fun), but it draws upon the basic plot arcs of the Skywalker Saga, and exploring that may have some appeal for them. You can safely assure them that they will prevail against it in the end, because, once again, Star Wars.
In base Star Wars cosmology those destined to be good will ultimately be good and evil will never prevail in the end. Eventually these characters either have to fall or be redeemed such that their alignments match or they have to be enemies, and if they all become dark they will betray and murder each other. These character arcs may fall outside the scope of your campaign, but they are the character arcs that canon Star Wars lore demands. It's all very cheesy, but that's Star Wars. Which is all simply to say that if your players simply want to play characters messing around in the Star Wars setting they can constantly murder hobo or be a Jedi that can never be tempted by the Dark Side, but that's not really Star Wars. Suggest to them that if they want to play proper Star Wars characters in a Star Wars story, there are limits which it is reasonable to ask them to follow which are also limits which may give you a little space to have this party function together in a campaign.