ci: Move building visual tests binary to separate step (#53440)

https://github.com/zed-industries/zed/pull/53408 did not solve the root
issue of the cache issues we were seeing with building the visual tests
binary.

Thus, moving this to a separate step here to test how fast it is and
removing it from the other test runs - it should not be there anyway and
especially not for the tests on release builds.

Release Notes:

- N/A
364ebfcc07Finn Evers committed on 4/8/2026, 10:23:58 PM· committed by GitHubparentc69a91b
4 files changedLine totals unavailable