WIP BibCheck: collection-based filters and timestamps

* Store the earliest date among last time webcoll was run and the last
  bibindex `last_update` as the `last_run`, instead of the last time the
  rule was initiated. This prevents a race condition where records
  inserted between a webcoll run and the beginning of the following
  bibcheck ran were never considered by bibcheck.
  (resolves #2387)

Reported-by: Samuele Kaplun <samuele.kaplun@cern.ch>
@dset0x Mmh... isn't this boolean condition all reverse to what it was supposed to be? I guess we would like to update the DB (WRT timestamps) only if none of `task_has_option('record_ids')`, `task_get_option('no_upload')` and `task_get_option('no_tickets')` are used.