Remove unneeded otel gem
What does this MR do and why?
Remove unneeded opentelemetry-instrumentation-active_model_serializers
gem.
Resolves thread: !148695 (comment 1875570990)
MR acceptance checklist
Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.