Remove the check for the current patch set, since this is not a
requirement of SubmitRuleEvaluator. It is also redundant for
canSubmit; all existing callers either pass in the current patch set
explicitly (e.g. QueryProcessor) or, in the case of Submit, have their
own check that the patch set is current.
The result of this is that canSubmit is now a thin wrapper around
SubmitRuleEvaluator and can be removed in a later change.
Change-Id: Ice4fd5f0af089f098eed9feadd43263189959995
ba4243ccfc