would there have been? We don't really know the First Orders plan after Kylo fails to bring rey to her.If it was about the characters changing their plan instead of Johnson ignoring the plot line that was set up in TFA, there would have to be a line in the movie about them changing plans due to new intel or whatever.
Jedi takes place several months after Empire. Even if Vader's first assumption is that Luke would try to go rescue Han at Jabba's (even though neither movie indicates this is Vader's thought process), how long should he have camped out over there?
Of course Vader knew that's how he got Luke to come to Cloud City. Han even makes a point about him not being asked any questions just being tortured. So Vader knows that Luke will risk himself to go after his friends.
It's the empire they have unlimted resources it seems like it would be a small price to pay to have some elite troopers there in Jaba's palace waiting. Not to mention they already have a outpost on Tatooiine.