There are a couple of tests relating to analytics which have extremely high memory consumption when coverage generation is enabled (over 70GB).

This happens because phpdbg and xdebug keep track of each line of code, each time that it is executed as part of their opcache logging functionality.

Although we don't actually generate coverage for these files right now, we have no way to prevent the opcache log from running against these files due to the nature of php-code-coverage.

It is (now) possible to do this via standard phpunit annotations - specifically the `@coversNothing` annotation. I had tried this before, but it was not working due to a bug in phpunit which I have now fixed (and has been released upstream).