add metrics for trial

[yeya24]

Signed-off-by: yeya24 yb532204897@gmail.com

What this PR does / why we need it:

Similar to #954, but for trial

Additionally, use prometheus.Registerer interface to register metrics, to avoid duplicate metrics registration in tests.

Release note:

---

This change is 

[k8s-ci-robot]

Hi @yeya24. Thanks for your PR.

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[gaocegege]

/ok-to-test
/lgtm

[hougangliu]

/approve

[k8s-ci-robot]

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