[1151441] fix i-test failures (2)
The i-tests actually set/restore rhq.server.high-availability.name sysprop
in the before/after methods.  This allows testng to jump around and execute
tests in different classes, in different orders, while the server name
remains correct for each test.  Update the server name caching
mechanism to reset the cache when sysprop changes are detected.  I don't
think this has any production use case, but it's required for testing,
doesn't cost much, and still keeps the original fix for this BZ intact.