Up to 4x performance regression compared to c8d7c19

[kit-ty-kate]

#5208 made it so that the dependency cone of the switch invariant is recomputed everytime the switch state changes.

The issues is that everytime a package is installed or removed, the switch state is changed so the invariant is recomputed.

This causes a sizeable performance regression for opam remove and opam upgrade (and less sizeable but still there for opam install). For example:

• with c8d7c19 opam remove -a patdiff takes 8 seconds on my machine
• after the merge of Compiler packages into invariant packages #5208 it now takes 30 seconds
• I've tried locally to remove the call to OpamSwitchState.universe from OpamSwitchState.dependencies but it still takes twice the time as before (15 seconds) due to OpamSwitchState.dependencies alone (taking itself between 0.1 and 0.2 seconds per call)

Also, I'm not sure how related this is to the performance issue but I've also noticed that the last dynamic line during opam install/remove (e.g. Processing 80/209: [dune: ocaml 9]) kept blinking and wasn't visible with master (0a174e1) but was always there with c8d7c19.
If this isn't related to the current problem we should create a separate issue to track this.