Instrument job_token_inbound_access_counter metric

What does this MR do and why?

Instrument job_token_inbound_access_counter metric

We add this metric to determine what is the level of legacy access vs non-legacy access.

Today, it is possible to use ProjectCiCdSetting#inbound_job_token_scope_enabled but this does not give a complete picture as we do not know whether cross-project access is taking place, or not.

Related issue: #366378

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