add dbName as required for spark metastore (#25259)

Co-authored-by: Zhenyu Zhou <zhezhou@microsoft.com>

Author: aim-for-better

specification/hdinsight/resource-manager/Microsoft.HDInsight/HDInsightOnAks/preview/2023-06-01-preview/hdinsight.json

@@ -2252,6 +2252,7 @@
       "description": "The metastore specification for Spark cluster.",
       "required": [
         "dbServerHost",
+        "dbName",
         "dbUserName",
         "dbPasswordSecretName",
         "keyVaultId"