codecov code should be fixed or disabled

[emteknetnz]

Codecov is being disabled from automatically running on the silverstripe account because it's causing segfaults

e.g.
https://github.com/silverstripe/silverstripe-blog/runs/7349442321?check_suite_focus=true
/home/runner/work/_temp/b2c83dc1-1b66-44c5-af39-62cd737a1bbb.sh: line 9: 5368 Segmentation fault (core dumped) phpdbg -qrr vendor/bin/phpunit --coverage-clover=coverage.xml

Either
a) investigate a fix the issue, likely would need to change from what use use for creating the coverage report
b) give up on the idea of code coverage entirely and remove the code from gha-ci, as well as the phpcoverage_force_off option from gha-generate-matrix and any modules that use the option

[GuySartorelli]

Note also that with force codecov enabled, modules which have no tests still get a codecov job created (e.g. https://github.com/silverstripe/silverstripe-testsession/runs/7380667649?check_suite_focus=true)