PageGrid Issue on Category and Product Pages Fixed

In rare cases it could happen that wrong content was delivered from the cache. The reason was a problem with the identity of the PageGridCacheKey.

(CMS-19416)

CapBlobHandlerTest doesn't fail even if mediatransform.xml is populated

There has been some refactoring since 2101.2 and the bug is not reproducible since 2101.3.

(CMS-18988)