update aws amplify from v5 to v6 and fix its test

[timheilman]

per https://github.com/cypress-io/cypress-documentation/pull/5610 , here are the updates applied to the cypress-real-world-app to fix the breaking changes in the amplify-js version 6 release

closes #1459

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[timheilman]

sorry for the re-review request. Fixing the yarn.lock conflict dismissed the prior review.