Remove several obsolete maint scripts.

Remove several obsolete maint scripts.
* userDupes and cleanupDupes are obsolete, referring to old indexes. Their backing code is still used for updaters but the front-ends are now useless.
* importPhase2 was not functional for a long time, no reason to keep it in current code.
* dumpReplayLog was experimental and didn't really do anything, and used 1.4 schema to boot. :)