Remove select2 implementations
The codebase currently contains a number of dropdowns/selects that leverage the `select2` jQuery plugins. As we are trying to move away from jQuery, and because of https://gitlab.com/gitlab-org/gitlab/-/issues/368880, we would like to initiate the removal of the package by migrating existing usages to some other components.
In this epic, we'll track individual implementations and their migration to alternative approaches. Once all migrations are completed, we'll do another pass at finding references to `select2` before removing the dependency altogether.
## Coming for the ~"Pajamas Migration Day"?
:wave: Hope you're having a great ~"Pajamas Migration Day"!
Please note that some of these issues might require more than a day's work. In some cases, you might even need to re-refine the issue and to involve ~UX before getting started with the implementation.
If an issue caught your eye, but you feel like you won't be able to address it, you can also help by making sure it's properly labelled and nothing misses from its description.
If you do pick up one of the tough ones, be assured that your MR will count towards the ~"Pajamas Migration Day" even if it takes a while for it to get merged, so don't shy away from that pesky `select2` dropdown you've always wanted to get rid of!
### Looking for low handing fruits?
We have identified a few issues that might only require you to remove some obsolete code:
* https://gitlab.com/gitlab-org/gitlab/-/issues/374118+
* https://gitlab.com/gitlab-org/gitlab/-/issues/374103+
* https://gitlab.com/gitlab-org/gitlab/-/issues/374013+
If you pick up one of those, start by investigating whether the code actually is unused as only a quick analysis was done when creating those issues. If you find out that the code actually is still needed, please document your findings in the corresponding issue :bow:
epic