fix typo in the newly added environment variable

Author: na-ji

metadata/supported-configurations.json

@@ -139,9 +139,9 @@
     "DD_DATA_STREAMS_BUCKET_DURATION_SECONDS": ["A"],
     "DD_DATA_STREAMS_ENABLED": ["A"],
     "DD_DBM_INJECT_SQL_BASEHASH": ["A"],
+    "DD_DBM_ALWAYS_APPEND_SQL_COMMENT": ["A"],
     "DD_DBM_PROPAGATION_MODE": ["A"],
     "DD_DBM_TRACE_PREPARED_STATEMENTS": ["A"],
-    "DB_DBM_ALWAYS_APPEND_SQL_COMMENT": ["A"],
     "DD_DISTRIBUTED_DEBUGGER_ENABLED": ["A"],
     "DD_DOGSTATSD_ARGS": ["A"],
     "DD_DOGSTATSD_HOST": ["A"],