optimise indexer active crawling process

[t83714]

optimise indexer active crawling process

The indexer's active crawling process can be improved in the following areas:

• The indexer should temporarily disable the indexer webhook after the active crawling process starts and re-enable the webhook once it completes.
• The indexer should record the latest event number of the system, and if this number is higher than the event number that the indexer has processed up to, the indexer webhook lasteventid will be replaced with this number.
  • This makes sure indexer will not re-do the events that have been processed by the active crawling process.