[azure-sdk-for-js] test folder structure - managing env.ts and env.browser.ts files

[HarshaNalluru]

I've seen env.ts and env.browser.ts files in the generated test/ folders for the SDKs in azure-sdk-for-js.

Starting from recorder v2, we did not need env.ts and env.browser.ts files.

Currently, all the packages in azure-sdk-for-js depend on recorder v3 or v4

• importing these files(env.ts) while using recorder v3 does not break anything. But it is recommended to remove them.
• However, from recorder v4, importing these files(env.ts) will break the tests because of the switch from commonjs to esm.

TO DO

• remove env.ts and env.browser.ts files
• remove import "./env.js" or import "./env" or equivalent imports in test files
• If the mapping for browser for these is put in package.json, remove that too