metrics: add dml batch callback duration metric in grafana

[amyangfei]

What problem does this PR solve?

Issue Number: ref #5928

What is changed and how it works?

Add metric ticdc_sinkv2_txn_sink_dml_batch_callback in grafana template.

Check List

Tests

• Manual test (add detailed scripts or steps below)

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

None

[ti-chi-bot]

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[3AceShowHand]

/run-integration-test
/run-kafka-integration-test

[hi-rustin]

@amyangfei Could you please post some screenshots to show it? Thanks!

[ti-chi-bot]

@amyangfei: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
jenkins-ticdc/verify	b1cc289	link	true	/test verify

Full PR test history. Your PR dashboard.

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