fix(api-graphql): events ws connect sig

[iartemiev]

Description of changes

Sigv4 calculation for Event API WS Connect was incorrectly appending a /connect path to the request URL. This is required for GQL Realtime WS Connect, but breaks for Event API.

Issue #, if available

https://github.com/aws-amplify/amplify-js/issues/14001

Description of how you validated changes

• Manual - events & graphql realtime WS connect & sub with IAM/IdP
• E2Es: https://github.com/aws-amplify/amplify-js/actions/runs/11804564727

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)