IBX-12654: Fixed dynamic calls to static methods

[bnowak]

🎫 Issue	IBX-12654

Related PRs:

• IBX-12654: Enabled the PHPStan strict rule for dynamic calls to static methods phpstan#16

Description:

Replaces dynamic calls to static methods ($this->assertX(), static test helpers, ...) with self::/ClassName:: calls: 2 calls in 1 file. The staticMethod.dynamicCall strict rule itself is enabled in the linked ibexa/phpstan PR; this PR keeps CI green once that is released.

Both calls are $this->assertSame() inside a self::callback() closure in tests/lib/Component/ControllerComponentTest.php. php-cs-fixer's php_unit_test_case_static_method_calls rule deliberately skips closures, so they were changed by hand to self::assertSame(); composer fix-cs then made the closure static because it no longer uses $this.

For QA:

No functional change. CI (PHPStan, code style, unit tests) is the verification.

Documentation:

No client-facing impact.