Remove SUMMARY_GROUP_COUNT_PER_ACCOUNT support (for now)

This sub-query needs to be rewritten for the upcoming accounts
refactoring, but since it's @hide'ed and no one is using it, let's
just remove it for now.

I believe this count can be implemented efficiently using a join
(in a similar way we support SUMMARY_COUNT) rather than a subquery, but
this should be even easier after the refactoring.

Also when we re-implement this, we can just check if the projection
contains SUMMARY_GROUP_COUNT_PER_ACCOUNT, so we'll probably be able to
remove PARAM_RETURN_GROUP_COUNT_PER_ACCOUNT.

Change-Id: I3adc93cdf57280ab06b4a2cab77f834811178af8
2 files changed