Plugin Lucene version checker: use `Lucene.parseVersionLenient`

With commit 07c632a2d4dbefe44e8f25dc4ded6cf143d60e41, we now have a new Lucene.parseVersionLenient(String, Version) method which tries to find an existing Lucene version based on the two first digits X.Y of X.Y.Z String.

(cherry picked from commit 264d59c)