Add table property to inject delay in event processing

We have tests that verify the behaviors during event processing. We use global debug action like "--debug_actions=catalogd_event_processing_delay:SLEEP@2000" to inject the delay.
It'd be helpful to add a table property for the same which only affects processing events on that table. So we can control the delay more specifically.

This is pointed by csringhofer during the review of https://gerrit.cloudera.org/c/20986/8/tests/custom_cluster/test_web_pages.py#444