When handling members_MemberInvited event the query node should update the membership working group budget, as the runtime does not emit a separate event when working group budget is being decreased.

This has already caused a mismatch between chain state and query node state on mainnet:

• Query node state (https://pioneerapp.xyz/#/working-groups/membership / https://query.joystream.org/graphql):
  
  (Budget: 2000 JOY)

• Runtime state (https://polkadot.js.org/apps/?rpc=wss://rpc.joystream.org:9944/ws-rpc#/chainstate):
  
  (Budget: 1991,6 JOY)