admin: Remove `wiki-macros` on upgrade (or warn if it is non-empty).
admin: Remove `wiki-macros` on upgrade (or warn if it is non-empty).

Closes #9023.


git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@9249 af82e41b-90c4-0310-8c96-b1721e28e2e2

rbaumg/trac,rbaumg/trac,rbaumg/trac,rbaumg/trac