Updated date_formats to new dynamic_date_formats
Update core-types.asciidoc

Missing bracket
Update percolate.asciidoc

fix typo
[TEST] Wait for shards to be allocated before running testUpdateMappingDynamicallyWhilePercolating.

If the percolate request is executed soon enough, all shards fail and the
mapping is not actually updated.
Switch back to ConcurrentMergeScheduler

Load tests showed that SerialMS has problems to keep up with
the merges under high load. We should switch back to CMS
until we have a better story to balance merge
threads / efforts across shards on a single node.

Closes #5817
[DOCS] Update merge docs to reflect the max_merge_at_once property