br: use the correct unit for pausing schedulers (#33545)

[ti-srebot]

cherry-pick #33545 to release-6.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/33817

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---

Signed-off-by: Ryan Leung rleungx@gmail.com

What problem does this PR solve?

Issue Number: close #33546.

Problem Summary: The unit for TTL of schedulers is not correct. We should use second as the unit.

What is changed and how it works?

Check List

Tests

• Manual test

1. start a cluster with TiUP
2. use lightning to import data
3. kill lightning with kill -9

Here is the log of PD:

[2022/03/29 14:26:07.097 +08:00] [INFO] [handler.go:272] ["pause scheduler successfully"] [scheduler-name=balance-region-scheduler] [pause-seconds=300]
[2022/03/29 14:26:07.097 +08:00] [INFO] [handler.go:272] ["pause scheduler successfully"] [scheduler-name=balance-leader-scheduler] [pause-seconds=300]
[2022/03/29 14:26:07.098 +08:00] [INFO] [handler.go:272] ["pause scheduler successfully"] [scheduler-name=balance-hot-region-scheduler] [pause-seconds=300]

Release note

Fix the issue that the schedulers won't be resumed after BR/Lightning exits abnormally.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• glorv

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[ti-srebot]

/run-all-tests

[ti-srebot]

@rleungx you're already a collaborator in bot's repo.

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/187a8fb8c8ab4254e5c2a287d4c6dca3a9b8694a