Remove branch ee- prefix and -ee suffix in EE/CE checks

ee-files-location-check and ee-specific-lines-check was originally designed for the EE only MR, as a reminder of porting stuffs to CE or move the EE only stuffs in ee/ directory.

That's why we match against *BRANCH-NAME*, assuming that people would name their branch like BRANCH-NAME-ce or ce-BRANCH-NAME.

But actually it's more often that we're making CE MRs, which requires an EE MR to resolve the conflicts. In this case, we ended up with BRANCH-NAME-ee or ee-BRANCH-NAME, which won't match against the CE branch like BRANCH-NAME.

If we could cut off the ee- prefix and -ee suffix then it would work better for this case.