Currently if the Lucene version is `X.Y.Z-snapshot-{gitrev}`, then we will
expect the docs to have `X.Y.Z-snapshot` as a Lucene version. I would like
to change it to `X.Y.Z` so that this doesn't need changing when we move from a
snapshot to a final release.
The Lucene version constants for 5.4.1 and 5.5.0 are wrong, they are
listed as 6.5.0 instead of 6.5.1. This commit fixes these issues, and
adds a test to ensure that this does not happen again.
Relates #24923