Merge coverage both Mocha and Jest

[michielmulders]

Expected behavior

Now, we store coverage results in two different places (root and /test).
Change paths to have them stored together and update Jenkins cleanup step (post step) for the Jest testing steps. In short, combine the results of both test suites.

Actual behavior

Different folders, two reports.

Steps to reproduce

npm run jest:unit
npm test -- mocha:default:functional:get

Which version(s) does this affect? (Environment, OS, etc...)

1.6.0

@yatki

[yatki]

This issue will be done as part of #2946