Correctly update redirects of existing pages
We were incorrectly indexing cross-namespace redirects that were not indexed in the old update pipeline. Relatedly we were indexing the prefixed title in the redirect array, but the search index is expecting the unprefixed title to be here.
Update the way we handle these redirects to match the old pipeline, and thus how the query and presentation side of CirrusSearch expect this data to be stored.
Bug: T372446