feat: Decouple framework plugins from pkg/epp/metrics via MetricsRecorder interface

[gyliu513]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Summary

• Define a MetricsRecorder interface in pkg/epp/framework/interface/plugin to abstract metrics recording, following the dependency inversion principle
• Add a concrete Recorder implementation in pkg/epp/metrics that delegates to existing package-level functions
• Inject MetricsRecorder through the Handle interface so framework plugins no longer directly import pkg/epp/metrics
• Remove all pkg/epp/metrics entries from the framework import exception list in hack/verify-framework-imports.go

Motivation

Framework plugins under pkg/epp/framework/ should not import upper-layer packages like pkg/epp/metrics. Previously, 7 plugin files had direct pkg/epp/metrics imports tracked as exceptions in verify-framework-imports.go.

This PR eliminates those violations by introducing a MetricsRecorder interface at the framework layer and injecting the concrete implementation via Handle.

Which issue(s) this PR fixes:

Fixes #2785

Does this PR introduce a user-facing change?:

feat: Decouple framework plugins from pkg/epp/metrics via MetricsRecorder interface

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: gyliu513
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