fix: update regex for namespace query in Grafana dashboard (#3002)

Signed-off-by: mohammedabdulwahhab <furkhan324@berkeley.edu>
Signed-off-by: zhongdaor <zhongdaor@nvidia.com>

Author: mohammedabdulwahhab

deploy/logging/grafana/dashboard.json

@@ -108,7 +108,7 @@
           "options": [],
           "query": "label_values(namespace)",
           "refresh": 1,
-          "regex": "",
+          "regex": ".+",
           "skipUrlSync": false,
           "sort": 1,
           "type": "query"

deploy/logging/grafana/logging-dashboard.yaml

@@ -118,7 +118,7 @@ data:
             "options": [],
             "query": "label_values(namespace)",
             "refresh": 1,
-            "regex": "",
+            "regex": ".+",
             "skipUrlSync": false,
             "sort": 1,
             "type": "query"