[BUG]: State "is_latest" does not get reset for older extension versions

[cnmarco]

T3Monitor\T3monitoring\Service\DataIntegrity::getLatestExtensionVersion() sets the flag is_latest = 1 for the last major release of each extension version. But it does not reset that flag for versions that had is_latest = 1 before. Thus, multiple versions of the same extension may be marked as "is_latest". This leads to an incorrect count of outdated extension versions.