[PSM Interop] Fix the 10-minute-teardown issue in GAMMA tests (#34560)

We shouldn't just set `termination_grace_period_seconds=600` by default
for all gamma tests extending `GammaXdsKubernetesTestCase`.

This is what's causing the deployment deletion issue:

> `framework.helpers.retryers.RetryError: Retry error calling
framework.xds_k8s_testcase.IsolatedXdsKubernetesTestCase.cleanup: 1
attempts exhausted. Last exception: RetryError: Retry error calling
framework.infrastructure.k8s.KubernetesNamespace.get_deployment: timeout
0:05:00 (h:mm:ss) exceeded. Check result callback returned False.`

We wait for 5 minutes, while the deployment is happily handing for 10.
Then the second cleanup retry kills it - but not before waiting for
another 5 minutes.

I think `self.force = False` may be solving another issue triggered by
the get_deployment retry timeout: because we start over deleting the
resources by name and some of them are deleted from the first attempt we
get 404. And I'm pretty sure we don't do error-handling correctly when
deleting CRD-based resources - which cascades into even more unnecessary
retries.

tools/run_tests/xds_k8s_test_driver/framework/test_app/runners/k8s/gamma_server_runner.py

@@ -70,7 +70,7 @@ class GammaServerRunner(KubernetesServerRunner):
         safilter_name: str = "ssa-filter",
         sapolicy_name: str = "ssa-policy",
         bepolicy_name: str = "backend-policy",
-        termination_grace_period_seconds: Optional[int] = None,
+        termination_grace_period_seconds: int = 0,
         pre_stop_hook: bool = False,
     ):
         # pylint: disable=too-many-locals

tools/run_tests/xds_k8s_test_driver/framework/xds_gamma_testcase.py

@@ -30,16 +30,13 @@ XdsTestServer = server_app.XdsTestServer
 
 logger = logging.getLogger(__name__)
 
-# We never actually hit this timeout under normal circumstances, so this large
-# value is acceptable.
-_TERMINATION_GRACE_PERIOD_SECONDS = 600
-
 
 # TODO(sergiitk): [GAMMA] Move into framework/test_cases
 class GammaXdsKubernetesTestCase(xds_k8s_testcase.RegularXdsKubernetesTestCase):
     server_runner: GammaServerRunner
     frontend_service_name: str
     pre_stop_hook: Optional[bool] = None
+    termination_grace_period_seconds: int = 0
 
     def setUp(self):
         """Hook method for setting up the test fixture before exercising it."""
@@ -113,7 +110,7 @@ class GammaXdsKubernetesTestCase(xds_k8s_testcase.RegularXdsKubernetesTestCase):
             network=self.network,
             debug_use_port_forwarding=self.debug_use_port_forwarding,
             enable_workload_identity=self.enable_workload_identity,
-            termination_grace_period_seconds=_TERMINATION_GRACE_PERIOD_SECONDS,
+            termination_grace_period_seconds=self.termination_grace_period_seconds,
             pre_stop_hook=self.pre_stop_hook,
         )
 

tools/run_tests/xds_k8s_test_driver/tests/gamma/affinity_test.py

@@ -34,6 +34,11 @@ RpcTypeUnaryCall = xds_url_map_testcase.RpcTypeUnaryCall
 
 _REPLICA_COUNT = 3
 
+# TODO(rbellevi): set this property on the prestop hook test class
+# We never actually hit this timeout under normal circumstances, so this large
+# value is acceptable.
+# termination_grace_period_seconds: int = 600
+
 
 class AffinityTest(xds_gamma_testcase.GammaXdsKubernetesTestCase):
     def getClientRpcStats(