Revert "Issue #3402444 by mondrake, Spokje, neclimdul, catch: Deprecate Test Suites, no longer available in PHPUnit 10"

This reverts commit dccd3221.

Issue #3402444 by mondrake, Spokje, neclimdul, catch: Deprecate Test Suites, no longer available in PHPUnit 10

Issue #3129508 by Lal_, daffie, Suresh Prabhu Parkala: Change multiple dirname()'s into a single dirname() with the use of the second parameter of dirname()

Issue #2499239 by Mile23, neclimdul, alexpott, jhedstrom, Mixologic, Crell, Xano, dawehner: Use test suite classes to discover different test types under phpunit, allow contrib harmony with run-tests