#628 Removed unnecessary scripts (used on Travis)

[pomek]

Suggested merge commit message (convention)

Other (tests): Removed unnecessary scripts after merging the main repository to the monorepo. Closes #628.

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Additional information

I am not sure about BREAKING CHANGE note. We're removing files but they were created for CI purposes. Public API of any package didn't change but npm scripts from ckeditor5-dev-tests have been removed. Help needed.

[coveralls]

Coverage decreased (-1.8%) to 89.311% when pulling e3def16 on i/628 into 24b718d on master.

[mlewand]

All in all looks good 👍

There's one mrgit mention remaining:

ckeditor5-dev/packages/ckeditor5-dev-env/lib/release-tools/tasks/releasesubrepositories.js

Line 641 in 177d2e3

logDryRun( 'It will also work using mrgit: `mrgit exec "git clean -f"`' );

I'll remove this with a separate commit in a minute.

[mlewand]

And agree that should be a major breaking change, we're removing a publicly available binaries. Given that we'll have other major BCs soon I don't think it's an issue for us.