'use strict' is unnecessary inside of modules.eslintstrict

[Pfed-prog]

Describe the bug
'use strict' is unnecessary inside of modules eslint: strict

To Reproduce
Steps to reproduce the behavior:

Go to:
aegir\actions\bundle-size\utils.js
aegir\actions\bundle-size\index.js

Expected behavior

Remove 'use strict'

Screenshots
If applicable, add screenshots to help explain your problem.

[achingbrain]

Anywhere use strict is still present is a hold-over from the pre-esm, pre-typescript days and it should be removed - please open PRs to any projects where you find this!

[SuchitraSwain]

I am working on this @achingbrain

[SuchitraSwain]

#1848

Please review @achingbrain @Pfed-prog