The new `prioritize_exact_search_match` can be used to force the search
algorithm to prioritize exact term matches in title when ranking results.
This is scoped narrowly to titles for cases such as a topic titled:
"organisation chart" and a search of "org chart".
If we scoped this wider, all discussion about "org chart" would float to
the top and leave a very common title de-prioritized.
This is a hidden site setting and it has some performance impact due
to double ranking.
That said, performance impact is somewhat mitigated cause ranking on
title alone is a very cheap operation.
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