fix: dbal compatibility of local gateway readers

[Nikolas Evers (vintagesucks)]

resolves shopware/shopware#18904

• AbstractReader::addTableSelection() used introspectTableByUnquotedName() (DBAL 4.4+) and getObjectName() (DBAL 4.3+), so local gateway reads failed on installs whose lockfiles contain an older DBAL
• the new Extension Verifier (lowest) job uses shopware-cli via shopware/github-actions/extension-verifier to validate the plugin against its lowest resolvable dependencies to catch issues like this in CI in the future
• pre-existing verifier findings fixed in code instead of starting an ignore list (76549b2)
• dropped a setAccessible() call that platform now rejects (follow-up to ci: enforce the test reflection ban with PHPStan instead of the Danger gate shopware#18777) → fix: phpstan #67

example output from temporarily reintroducing the issues:

src/Profile/Magento/Gateway/Local/Reader/AbstractReader.php
  91  error    [phpstan/method.notFound]  Call to an undefined method Doctrine\DBAL\Schema\AbstractSchemaManager::introspectTableByUnquotedName().

✖ 1 problems (1 errors, 0 warnings)