Revert "contint: reduce duplication with mediawiki::packages"

webserver::php5 declares the same package with an if ! defined
guard, which is not robust (it depends on the parse-order of manifests,
which is not specified), leading to duplicate def'n errors on gallium.

This reverts commit be44bbdad242fa0731fc915acb41de43433d7b72.

Change-Id: I582955fab83ee6f2e505bdac39532aa837c99e23
Merge "Revert "contint: reduce duplication with mediawiki::packages"" into production