Remove stray debugging code.
Bump crispin connection pool size.

I think we were using up all the connections now that we're syncing the
Trash/Spam/Inbox and All folders. This caused execution of
mailsync.backends.gmail.download_queued_threads to hang at line 347 when
getting a new crispin client, and lead to new messages not being processed
promptly by a running sync.

Since we need to revisit this pooling anyways (T29), simply bump the connection
pool size for now. Note that it can't be made arbitrarily large, or imaplib may
fail with 'too many simultaneous connections'.