Bug 1042190 - [Email] Improve IMAP retry logic.

I don't think that you want this to succeed.  We want it to fail because we give up.  That's also how we get closure from this test case and are sure we didn't retry more than we should have.  Arguably you may also want to be able to assert about the fawlty socket still having some precommands stacked up.

I think this also means you want more connection expectations below