Bug 800402 - [email] UI: Show the number of unread messages in the message-list header after the folder name

I'm assuming this file was speculatively copied from test_activesync_recreate and then you realized what you really wanted to create was test_storage_upgrade since it's the same as the former except with the comment on the last line removed.  Also, the test only passes for ActiveSync, etc. etc.  So let's remove it from here and test-files.json

Plus, I think test_storage_upgrade is basically enough coverage for us (in conjunction with human reviewer stuff).  test_activesync_recreate exists because the syncblocked stuff is complicated and has a lot of moving parts.  The header counting/etc. is relatively straight-forward and unit testing coverage is sufficient.