fix: for CI failures in playground e2e test

[ericswanson-dfinity]

Description

A recent change to mops has added some logging output in CI. This makes its way to the moc command-line, which then fails.

		if (process.env.GITHUB_ENV) {
			console.log('Running in GitHub Actions, reducing threads to 4');
			threads = 4;
		}

See the first commit in this PR, which doesn't change anything that would matter, but fails due to passing this message along to moc:

"Running" "in" "GitHub" "Actions," "reducing" "threads" "to" "4" "--package" "base" ".mops/[email protected]/src" "--package" "splay" ".mops/[email protected]/src"' failed with exit status 'exit status: 1'.

The second commit in this PR filters the output of mops sources using grep, which demonstrates that the console.log() message is going to stdout.

How Has This Been Tested?

See above.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[ericswanson-dfinity]

@ZenVoich can you make it so mops only outputs --package <path> to stdout, and anything else goes to stderr?

[ZenVoich]

@ericswanson-dfinity yes, removed extra console.log in mops 0.27.3