Do not execute compare action on mousedown events

[rafeca]

Closes #9971

Description

This PR removes the call to executeCompare() that was performed on mousdedown events against the compare branch list.

Context

Before this PR, two executeCompare() calls got executed when clicking on an item on the compare branch list: the first one happens on the mousedown event (the one I'm removing) and the second one on the click event (which happens after the mouseup event).

This caused an issue when the first executeCompare() call finished before the click event happened:

The executeCompare() action would update the filter text of the branch list with the selected branch name, causing the filter to be applied and therefore the branch list to get updated.

Then, when the second executeCompare() function was called it could potentially use another branch since the list elements could get updated.

In most situations where using a branch name as a filter won't match other branch names this didn't cause an issue, since after the first executeCompare(), the list of branches would only contain a single branch (the clicked branch) and the second executeCompare() action would be done against no item (and therefore ignored) or against the correct branch:

But this could cause an issue in some scenarios where a branch name is a subset of another branch name, for example when having a branch called X and another one called XY. In this case the initial list would sort the branches by most recent ones:

But once the user clicks on the X branch and the executeCompare() action gets called, the filtering gets applied and the order of displayed branches changes:

(this can be seen more clearly on the "Screenshots" section below).

About this PR

The call that I removed was introduced in #4412 to address an issue that is not present anymore in the compare branch UI (I've tested it with the changes of this PR), and I think that this is because with #4751 (which was merged a bit later) the whole need of the two executeCompare() calls is not needed anymore.

Still, the logic of the compare branches UI is quite complex and I had a bit of trouble understanding all the different scenarios and how things play together, so it's possible that I'm missing something (I also found a couple of existing bugs while testing this PR which I'll document separately).

Screenshots

Before:

After:

Release notes

Notes: [Fixed] Select Branch to Compare no longer selects wrong branches

[tierninho]

Nice job ✨ Verifying all looks good now with the changes.

[niik]

This PR was a joy to read @rafeca, great investigation and I really love that you provided links to where this was originally introduced, that always helps me build confidence in changes!