Remove deferSpec=20220824 from the response headers

[jer-k]

Fixes https://github.com/apollographql/apollo-server/issues/7909

In the issue I noted

Is there any reason to add the deferSpec=20220824 to the response header? Without it Apollo Client behaves properly and the devtools are able to preview the response data.

Unfortunately no response on the issue but I couldn't find any information as to why deferSpec would need to be in the response headers. If there is a need for it then this PR can be closed.

By removing it the Preview pane in devtools is able to display the deferred data

Before:

After: .

Tests

I updated the existing tests as this isn't adding anything net new