Core TravisCI not submitting results to hosting automated tests.

[kirasong]

This is a followup to: ​https://github.com/WordPress/wpdev-docker-images/issues/22

For anyone who isn't familiar with the distributed automated tests, the WordPress Hosting Team has a distributed automated test project that ​collects PHPUnit test results from hosts.

As part of this, WordPress.org's TravisCI reports to that page. Currently, this is used to email hosts when Core's tests are passing, but theirs are not.

The packages required are there now (thanks @pento!), but it looks like the API key isn't making its way to the reporter:
​https://travis-ci.com/github/WordPress/wordpress-develop/jobs/316610104#L3394

I'll attach a patch shortly.

[kirasong]

Pass API key to reporter in docker-compose.

[kirasong]

Added 49846.diff​.

This appears to work as expected on my Github fork with an alternate API key.

The tests still aren't able to pull envionment information for Imagick or MySQL (as is visible ​in these results), but it should restore result submission and pass/fail.

[kirasong]

Thanks much @SergeyBiryukov!

I'll get this committed.

[kirasong]

In 47556:

Tests: Pass API key to distributed test reporter.

Pass environment variable for test reporter API key to
docker-compose so that it can authenticate and submit results
to the hosting distributed tests.

Props SergeyBiryukov, mikeschroder.
Fixes #49846.