misc: Replace LayerCI reference with Webapp.io

[ianwalter]

• Closes

Additional details

Steps to test

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation?
• Have API changes been updated in the type definitions?

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[jennifer-shehane]

Context: https://webapp.io/blog/layerci-has-rebranded-to-webapp-io/

[emilyrohrbough]

These changes look good to me, though we also need update our CI docs found here to

1. remove the stale example referencing LayerCI
2. add a note that Cypress versions less than 3.15.0 will need to manually provide the CI ENVs to correctly send their SCM to the Cloud. https://docs.cypress.io/guides/continuous-integration/introduction#Git-information

[emilyrohrbough]

@ianwalter Let us know when this is ready for review!

[jennifer-shehane]

@ianwalter Do you have time to complete this PR?

[ianwalter]

@jennifer-shehane Sorry, still trying to find the time! 😅

[ianwalter]

Closing in favor of #28874