Add watchdog timeout event test (sonic-net#13468)

### Description of PR
Summary:
Fixes # (issue)26636373

### Approach
#### What is the motivation for this PR?

Add event for watchdog timeout

#### How did you do it?

Create mock test service that will sleep and therefore not send watchdog signal. This will generate watchdog timeout event

#### How did you verify/test it?

Manual test/Pipeline

tests/telemetry/events/event_utils.py

@@ -12,6 +12,21 @@
 PUBLISHED = 1
 
 
+def add_test_watchdog_timeout_service(duthost):
+    logger.info("Adding mock watchdog.service to systemd")
+    duthost.copy(src="telemetry/events/events_data/test-watchdog-timeout.service", dest="/etc/systemd/system/")
+    duthost.shell("systemctl daemon-reload")
+    duthost.shell("systemctl start test-watchdog-timeout.service")
+
+
+def delete_test_watchdog_timeout_service(duthost):
+    logger.info("Deleting mock test-watchdog-timeout.service")
+    duthost.shell("systemctl stop test-watchdog-timeout.service", module_ignore_errors=True)
+    duthost.shell("rm /etc/systemd/system/test-watchdog-timeout.service", module_ignore_errors=True)
+    duthost.shell("systemctl daemon-reload")
+    duthost.shell("systemctl reset-failed")
+
+
 def backup_monit_config(duthost):
     logger.info("Backing up monit config files")
     duthost.shell("cp -f /etc/monit/monitrc ~/")

tests/telemetry/events/events_data/test-watchdog-timeout.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Test Watchdog Timeout
+
+[Service]
+Type=simple
+# This service will sleep for 2 minutes therefore not sending the signal to watchdog within the specified 1 min requirement
+# Since SIGABRT will be sent after watchdog times out due to no signal, it will crash the bash process and dump core
+# Added logic to trap the SIGABRT so that no core dump is dropped.
+ExecStart=/bin/bash -c 'trap "" SIGABRT; sleep 120'
+WatchdogSec=60s
+
+[Install]
+WantedBy=multi-user.target

tests/telemetry/events/host_events.py

@@ -4,6 +4,7 @@
 import time
 from run_events_test import run_test
 from event_utils import backup_monit_config, customize_monit_config, restore_monit_config
+from event_utils import add_test_watchdog_timeout_service, delete_test_watchdog_timeout_service
 from telemetry_utils import trigger_logger
 from tests.common.helpers.dut_utils import is_container_running
 from tests.common.utilities import wait_until
@@ -42,6 +43,14 @@ def test_event(duthost, gnxi_path, ptfhost, data_dir, validate_yang):
                  "event_down_ctr.json", "sonic-events-host:event-down-ctr", tag, False)
     finally:
         restore_monit_config(duthost)
+    add_test_watchdog_timeout_service(duthost)
+    try:
+        # We need to alot flat 60 seconds for watchdog timeout to fire since the timer is set to 60\
+        # With a base limit of 30 seconds, we will use 90 seconds
+        run_test(duthost, gnxi_path, ptfhost, data_dir, validate_yang, None,
+                 "watchdog_timeout.json", "sonic-events-host:watchdog-timeout", tag, False, 90)
+    finally:
+        delete_test_watchdog_timeout_service(duthost)
 
 
 def trigger_mem_threshold_exceeded_alert(duthost):