Replace `NO_CHANGES` with `HAS_GIT_CHANGES`

> IMO, `HAS_GIT_CHANGES=no` is much better than `NO_CHANGES=yes`.
I aligned with others, to avoid changing others in this PR.

_Originally posted by @luislard in https://github.com/inpsyde/reusable-workflows/pull/174#discussion_r1942926935_
            