Revert minor change to db-common.yaml

model/db-common.yaml

@@ -3,8 +3,6 @@ groups:
     type: attribute_group
     brief: 'Database Client attributes'
     attributes:
-      - ref: db.system
-        requirement_level: required
       - ref: db.name
         requirement_level:
           conditionally_required: If applicable.
@@ -21,6 +19,8 @@ groups:
           conditionally_required: >
             If readily available. Otherwise, if the instrumentation library parses `db.query.text` to capture
             `db.operation.name`, then it SHOULD be the first operation name found in the query.
+      - ref: db.system
+        requirement_level: required
       - ref: network.peer.address
         brief: Peer address of the database node where the operation was performed.
         requirement_level: