Ensure that --revert-annotation flag is not generated for everything stubs

Currently, "--revert-annotations" argument is erroneously being added to
"everything" stubs when no aconfig flags are defined. This change fixes
this by ensuring that the argument is only generated for non-everything
stubs.

Test: m
Bug: 379807097
Change-Id: Iafea74de07240ccf4a27badabd86203133e25697