Opentelemetry-js: coverage runs take 2 min out of every circleci build

[lizthegrey]

See https://circleci.com/gh/markwolff/opentelemetry-js/673 for instance -- the fact that each different JS version is repeating the same code coverage (6x) reports results in extensive queuing for the entire otel organization.

Can you consider only running full coverage reports on a subset of environments?

[bogdandrutu]

In Java we run coverage only for one version

[mayurkale22]

I think it makes sense to remove code coverage from each different JS version and keep only two coverage report -> node (maybe node:11) and browser (node:12-browsers).

Also, somehow Install Dependencies job takes > 3m almost every time, need to do some investigation.

[mayurkale22]

Per SIG, these are the action items:

1. Merge lint and docs jobs.
2. Only install doc and lint dependencies (not a full install) - full install takes > 3mins.
3. Only run coverage on latest node and browser build
4. Investigate current caching mechanism

[lizthegrey]

Thank you! Your sister SIGs appreciate it.

[mayurkale22]

Merge lint and docs jobs.

Done in #495

Only install doc and lint dependencies (not a full install) - full install takes > 3mins.

Done in #498

Only run coverage on latest node and browser build

Done in #496

Investigate current caching mechanism

Done in #514

Also, we have removed duplicate compile step(#510) and redundant test from types package (#511).

Feel free to reopen the issue if there's something that all of these doesn't solve.

[lizthegrey]

Thanks a million!