Primary ids are only incremented on the main branch. For release branches
only patch ids will be created. The primary id validation won't always
work on release branches because only some of the primary ids will be
backported.

This commit skips primary id validation if we are sure we are on a
release branch. We can tell this by looking at the current upper bound
compared to other upper bounds. If there is a newer one, we know we are
on a release branch. If there isn't a newer one, we _might_ be on a
release branch, or on main, but in this case doing primary id validation
is ok because there's effectively no difference, we are looking at the
latest upper bound.