[chore] Bump splunk from 9.3.0 to 9.4.0

[jvoravong]

Description:

• This dependency is only used in testing

[jvoravong]

Tried to see if this was a quick upgrade. When starting to use 9.4.0 these errors happened in tests randomly. Closing this PR since this wasn't a quick change.

Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_label_collection[pod-w-index-wo-ns-index-pod-anno-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_label_collection[pod-wo-index-w-ns-index-ns-anno-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_label_collection[pod-w-index-w-ns-index-pod-anno-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_custom_metadata_fields_annotations[pod-w-index-wo-ns-index-pod-anno-pod-value-2-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_custom_metadata_fields_annotations[pod-w-index-w-ns-index-pod-anno-pod-value-1-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}
FAILED k8s_logging_tests/test_config_logging.py::test_metric_index_from_annotations[test_metrics-1] - Exception: status code: 503 
 details: {"messages":[{"type":"WARN","text":"Search not executed: The minimum free disk space (5000MB) reached for /opt/splunk/var/run/splunk/dispatch. user=admin., concurrency_category=\"historical\", concurrency_context=\"user_instance-wide\", current_concurrency=0, concurrency_limit=5000","help":""}]}