Log the actual watchdog timeout in test error message (sonic-net#20520)

What is the motivation for this PR?
To improve test errror message and help with debugging test failure.

How did you do it?
Log the actual watchdog timeout returned by arm() in test error message , instead of the watchdog_timeout passed to arm()

How did you verify/test it?
Tested by running the test cases and checking the error message when the tests failed

Signed-off-by: Domingo <domingo@nexthop.ai>

Author: domingo-nexthop

tests/platform_tests/api/test_watchdog.py

@@ -265,8 +265,13 @@ def test_arm_too_big_timeout(self, duthosts, enum_rand_one_per_hwsku_hostname,
         if watchdog_timeout is None:
             pytest.skip('"too_big_timeout" parameter is required for this test case')
         actual_timeout = watchdog.arm(platform_api_conn, watchdog_timeout)
-        self.expect(actual_timeout == -1, "{}: Watchdog should be disarmed, but returned timeout of {} seconds"
-                    .format(self.test_arm_too_big_timeout.__name__, watchdog_timeout))
+        self.expect(
+            actual_timeout == -1,
+            "{}: Watchdog should be disarmed when configured with {} seconds, "
+            "but returned timeout of {} seconds".format(
+                self.test_arm_too_big_timeout.__name__, watchdog_timeout, actual_timeout
+            ),
+        )
         self.assert_expectations()
 
     @pytest.mark.dependency(depends=["test_arm_disarm_states"])
@@ -275,6 +280,11 @@ def test_arm_negative_timeout(self, duthosts, enum_rand_one_per_hwsku_hostname,
 
         watchdog_timeout = -1
         actual_timeout = watchdog.arm(platform_api_conn, watchdog_timeout)
-        self.expect(actual_timeout == -1, "{}: Watchdog should be disarmed, but returned timeout of {} seconds"
-                    .format(self.test_arm_negative_timeout.__name__, watchdog_timeout))
+        self.expect(
+            actual_timeout == -1,
+            "{}: Watchdog should be disarmed when configured with {} seconds, "
+            "but returned timeout of {} seconds".format(
+                self.test_arm_too_big_timeout.__name__, watchdog_timeout, actual_timeout
+            ),
+        )
         self.assert_expectations()