relay: fix bug of relay metrics being recorded only once (#1748)

[ti-chi-bot]

This is an automated cherry-pick of #1748

What problem does this PR solve?

https://asktug.com/t/topic/93363/7

What is changed and how it works?

wrap the ticker listener in for loop so we can continuously receive the events.

Check List

Tests

• Manual test (TODO)

Code changes

Side effects

Related changes

• Need to cherry-pick to the release branch
• Need to be included in the release note

[lance6716]

/lgtm

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[lance6716]

/merge

[ti-chi-bot]

@lance6716: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• glorv
• lance6716

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[lance6716]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: eefb1d7