Invalidate ES cache when namespaces moved

Right now we are invalidating project cache when projects are moved from unindexed to indexed namespaces. Investigate if this needs to be done when a child namespace is moved from an unindexed namespace to an indexed namespace. This would only occur when index limiting is enabled for namespaces.

The following discussion from !50712 (merged) should be addressed:

• @DylanGriffith started a discussion: (+2 comments)

  This appears to be unused. But it makes me think that this may also be needed for a separate caching bug where the child namespaces may be moved from an unindexed to an indexed project and group search may revert to basic search. We don't need to tackle that with this MR as I think it's a separate bug but maybe worth checking and creating an issue about. If we don't need this method in this MR we should take it out until we need it.