Fix CircleCI test result paths.

[aaronweeden]

Description

This PR fixes the paths to the XML test results in the CircleCI config. Some of the paths were set to /tmp/phpunit, and some were set to ~/phpunit. As a result, the directory /tmp/phpunit was created, but the test results were written to ~/phpunit, which was assumed to be a file rather than a directory, and then CircleCI stored /tmp/phpunit, which was empty. This PR sets all of the paths to ~/phpunit rather than /tmp/phpunit to be consistent with the CircleCI config of the xdmod repository. It also gives filenames to each of the tests that use --log-junit so that the results are saved to files rather than being output to the terminal.

Tests performed

I checked the build-fresh_install-rocky8 and build-upgrade-rocky8 checks to make sure the test results show up in the "TESTS" tab, that each of the CircleCI steps that write to ~/phpunit do not list any errors, and that the "Uploading test results" step archives the following test results:

* /root/phpunit/component.xml
* /root/phpunit/integration.xml
* /root/phpunit/xdmod-supremm-regression-centerdirector.xml
* /root/phpunit/xdmod-ui.xml

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project as found in the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.