t/workload_upgrade_runner_test: disable test in debug mode

transition v23.1 -> v23.2 seems to be flaky in debug mode and a
producer/consumer workload running

tests/rptest/tests/workload_upgrade_runner_test.py

@@ -21,6 +21,7 @@
 from rptest.tests.workload_dummy import DummyWorkload, MinimalWorkload
 from rptest.tests.redpanda_test import RedpandaTest
 from rptest.tests.workload_license import LicenseWorkload
+from rptest.utils.mode_checks import skip_debug_mode
 
 
 def expand_version(
@@ -245,6 +246,7 @@ def _check_workload_list(self,
     def cluster_version(self) -> int:
         return Admin(self.redpanda).get_features()['cluster_version']
 
+    @skip_debug_mode
     @cluster(num_nodes=4)
     def test_workloads_through_releases(self):
         # this callback will be called between each upgrade, in a mixed version state