Preserve request id in Cinder logs when creating boot volume

The method get_internal_tenant_context miss the overwrite
parameter in RequestContext.
Ref patch: https://review.opendev.org/#/c/247102/.

Change-Id: I47c57254adeee065600b7f0db95bee1f813463bf
Closes-Bug: #1869160

cinder/context.py

@@ -264,7 +264,8 @@ def get_internal_tenant_context():
     if project_id and user_id:
         return RequestContext(user_id=user_id,
                               project_id=project_id,
-                              is_admin=True)
+                              is_admin=True,
+                              overwrite=False)
     else:
         LOG.warning('Unable to get internal tenant context: Missing '
                     'required config parameters.')