Revert "nnimap.el: support additional expunge options"

Revert "nnimap.el: support additional expunge options"

This reverts commit 4e9baea6aba1633074889339dcc7cdc9d73880d3.

The patch broke fetching new mail:

Debugger entered--Lisp error: (error "Format specifier doesn’t match argument type")
  format("%d .*\n" (t ("OK" ("HIGHESTMODSEQ" "914696") "Expunge" "completed.") ("VANISHED" "1825937") ("0" "RECENT")))
  (looking-at (format "%d .*\n" sequence))
  (not (looking-at (format "%d .*\n" sequence)))
  (progn (while (and (not (bobp)) (progn (forward-line -1) (looking-at "\\*\\|[0-9]+ OK NOOP")))) (not (looking-at (format "%d .*\n" sequence))))