Revert "feat: no-floating-promises (#756)"

[danielbankhead]

This reverts commit c93e733.

This project property is breaking lint in the following libraries:

• https://github.com/googleapis/nodejs-googleapis-common
• https://github.com/googleapis/google-auth-library-nodejs
• https://github.com/googleapis/gaxios
• https://github.com/googleapis/nodejs-pubsub

Error message:

Parsing error: ESLint was configured to run on `<tsconfigRootDir>....` using `parserOptions.project`: .../tsconfig.json
However, that TSConfig does not include this file.

We should include this in the next major instead as the requires a coordinated release.

BEGIN_COMMIT_OVERRIDE
fix: revert feat: no-floating-promises
END_COMMIT_OVERRIDE