Autonomous Alarm Purge based on retention period

Autonomous Alarm Purge based on retention period

This commit introduces an autonomous purge mechanism for alarm event
records based on the retention period specified in the alarm service
configuration.

Previously, the "purge event" was used for clearing alarms. To improve
clarity, the "clear" and "purge" events have been split to better
distinguish their respective purposes.

Test Plan:
PASS - Successfully purges alarm event records that exceed the retention
       period.
PASS - Ensures that alarm event records not in "clear" or "acknowledged"
       status remain unaffected.
PASS - Verifies that clearing an alarm operates as expected.

Change-Id: I2414caa4929daf3efb1ccb9848f84ef69b80318f
Signed-off-by: Zhang Rong(Jon) <rong.zhang@windriver.com>