Break out quota refresh check code from quota_reserve()

This moves the logic that is checking if a quota refresh is needed into
a private method.

This is part of a larger series to refactor the quota_reserve method.

Partial-Bug: #1369605

Change-Id: I07fa1a5d53708f33b68a49186dbc5db15a1dbf17
Merge "Break out quota refresh check code from quota_reserve()"