Revert "Performance tweaks to Identifier package"

This reverts merge request !76093 (merged) due to many unit test failures: https://atlas-sw-build-logs.web.cern.ch/ciwww/CIWebArea/nicos_web_areaMRCIbuilds64BE9G13AthenaOpt/NICOS_TestLog_MR-76134-2024-11-22-18-47/ReleaseTests___unit-tests__unit-tests__m.html

cc @sroe