Align @defer v1 implementation with latest proposed spec updates

[alessbell]

While @defer support work is in flight (#10018), it has been implemented against a now-outdated version of the proposed spec.

This is a placeholder issue for aligning with the latest implementation (graphql-js PR here graphql/graphql-js#3659, spec edits PR here graphql/graphql-spec#742)

[jpvajda]

See graphql/defer-stream-wg#41

[jpvajda]

See graphql/defer-stream-wg#50

[alessbell]

Closing this as done as the latest changes have been incorporated as of c44b38c

[jpvajda]

@alessbell thank you! It's likely we'll have another change to consider in the future as the spec evolves and is ratified, but we can create that ticket when the time comes.