SqlBlobStore HOT FIX: remove caching from getBlobBatch
This is a TEMPORARY HACK to fix a problem with cached values
getting mixed up when using getBlobBatch(). As of the creation of this
patch, the actual cause is unknown. Caching should be put back once the
cause of the problem has been found.
Note that getBlobBatch is only used in maintenance scripts.
Removal of caching in that method has no effect on web requests.
getBlobBatch() was introduced in I56306c50a661 and is used by
RevisionStore::getContentBlobsForBatch(), which in turn is needed
by the Translate extension to remove its dependency on the deprecated
rev_text_id field.
Bug: T235188
Change-Id: I94c6f9ba7b9caeebaa9b055916f15f7bbdcd8fb6