refactor(api-graphql): apply WS.close to base class

[iartemiev]

Description of changes

Applying change from #13989 to the base class. Verified that this does not affect the Realtime provider. .close() is not accessible publicly and is not invoked internally on that provider.

Description of how you validated changes

• Code review
• Unit tests pass
• E2Es pass: https://github.com/aws-amplify/amplify-js/actions/runs/11709500317

Checklist

• [x] PR description included
• [x] yarn test passes
• [x] Unit Tests are changed or added
• [x] Relevant documentation is changed or added (and PR referenced)

[iartemiev]

fix vs refactor?

Refactor is more appropriate. Updated