This commit clarifies how we intend the spring-boot:repackage goal to
be used. As it operates on the source jar (or war) that must be
effectively up-to-date to produce an accurate result, the package phase
must have run.
Contrary to build-image that was designed to be used on the command-line
by forking a package lifecycle first, repackage does not do that. This
commit also clarifies that by providing a more focused error message.
Closes gh-22317
7607bf1ab8