Manually sort the item list so that tagListHash.contains tests work

Otherwise the individual tests in this testcase may work on the wrong
mails as libmaildir doesn´t sort the entry list anymore.

This is related to the nosorting change from review request 117975.

This needs to go into 4.13 branch as well before release of 4.13.2.

CCBUG: 334218

REVIEW: 118441