TestEnv can't handle component versions with a branch name in CI

If you use the =branch_name format for your component version files (GITALY_SERVER_VERSION, GITLAB_SHELL_VERSION, ...) in CI the component folder will be deleted and reinstalled every time TestEnv.init runs. This behavior is acceptable for local development since it keeps you up to date with your component's branch, but in CI is unnecessary and can cause problems; specifically, when used for the Gitaly version, this behavior can delete the socket file while Gitaly is running, making the test code unable to connect with the test Gitaly instance.