fix(gen2-migration): graphql additional auth providers escape hatch compilation error

[iliapolo]

Description of changes

The escape that is currently being generated has a compilation error:

backend.data.resources.cfnResources.cfnGraphQLApi

Expected an assignment or function call and instead saw an expression.eslint[@typescript-eslint/no-unused-expressions](https://typescript-eslint.io/rules/no-unused-expressions)
Property 'cfnGraphQLApi' does not exist on type 'AmplifyGraphqlApiCfnResources'. Did you mean 'cfnGraphqlApi'?ts(2551)
types.d.ts(667, 14): 'cfnGraphqlApi' is declared here.

It should be:

backend.data.resources.cfnResources.cfnGraphqlApi

Description of how you validated changes

Manual test

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• Pull request labels are added

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