Improve test coverage of CLOBBER_CACHE_ALWAYS by having it also force

reloading of operator class information on each use of LookupOpclassInfo.
Had this been in place a year ago, it would have helped me find a bug
in the then-new 'operator family' code.  Now that we have a build farm
member testing CLOBBER_CACHE_ALWAYS on a regular basis, it seems worth
expending a little bit of effort here.