APIGOV33468 - fix remoteApiName_ prefix not stripped in metric API detail lookups

[sbolosan]

Fixes a bug where Azure (and any agent whose API ID equals its display name) traceability events showed "unknown" for Subscription, Product, ProductPlan, Quota, AssetResource, APIServiceRevision, consumer Application, api.owner, and api.apiServiceId — even when the correct AccessRequest and APIService were cached.

Root cause: ResolveIDWithPrefix falls back to prefixing the API name with remoteApiName_ when no real ID is available. Five separate cache-lookup call sites only ever stripped the remoteApiId_ prefix, never the remoteApiName_ fallback, so the lookup key never matched and every downstream field defaulted to unknown.

Adds StripSummaryEventPrefix in pkg/transaction/util/util.go, which strips both possible prefixes, and points all five affected call sites at it:

1. GetAccessRequest (util.go)
2. ResolveAPIOwner (ownerresolver.go)
3. buildSummaryAPIDetail's apiServiceId fallback (v2event.go)
4. createAPIDetail (metricscollector.go)
5. buildAPIRef (metric/util.go)

Adds table-driven test coverage for all affected sites, including the name-fallback regression case specifically:

1. TestStripSummaryEventPrefix, updated TestResolveAPIOwner, TestBuildAPIRef, TestCreateAPIDetail,
2. TestBuildSummaryAPIDetailAPIServiceIDFallback.

No behavior change for any agent whose API ID never collapses to the name-fallback form (e.g. v7, webmethods) — verified live against azure-agents, webmethods-agents, and sample-agent with no regression.