Remove the git_push_execute_all_project_hooks feature flag

The git_push_execute_all_project_hooks gives us a way back to execute all hooks when pushing more than 3 (or whatever specified) branches or tags. By default the maximum number of hooks executed is 6 (3 branches, 3 tags).

After validating everything works as expected, we should remove this feature flag.

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The following discussion from !17874 (merged) should be addressed:

• @reprazent started a discussion: (+1 comment)

  Cool! Could you create an issue to remove the Feature flag please?