Revert "Fix online reindexing for plugins-dependent rules"
Loading plugins before activating the index breaks any plugin that
relies on the index. This is more of a problem in 2.15 since the
caches refer to the index, and therefore breaks any plugin that
relies on caches.
This reverts commit 86a1dd735cbd14dab9eb05a0b2dbfd862ce8c8d9.
Bug: Issue 10082