[SPARK-18010][CORE] Reduce work performed for building up the application list...

[SPARK-18010][CORE] Reduce work performed for building up the application list for the History Server app list UI page

## What changes were proposed in this pull request?
allow ReplayListenerBus to skip deserialising and replaying certain events using an inexpensive check of the event log entry. Use this to ensure that when event log replay is triggered for building the application list, we get the ReplayListenerBus to skip over all but the few events needed for our immediate purpose. Refer [SPARK-18010] for the motivation behind this change.

## How was this patch tested?

Tested with existing HistoryServer and ReplayListener unit test suites. All tests pass.

Please review https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark before opening a pull request.

Author: Vinayak <vijoshi5@in.ibm.com>

Closes #15556 from vijoshi/SAAS-467_master.