pd_client: add backoff for the reconnect retries (#15429)

[ti-chi-bot]

This is an automated cherry-pick of #15429

What is changed and how it works?

Issue Number: Close #15428
ref tikv/pd#6556

What's Changed:

 pc_client: add store-level backoff for the reconnect retries

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

In 50 TiKVs, 1M regions cluster: use pd-failpoint-binary, and ingest the failpoint.

1. enable fail point, like gRPC is throttling, cannot read from etcd.
   curl -X PUT -d 'return(10)' http://tc-pd-1.tc-pd-peer.csn-simulator-big-cluster-vd62g.svc:2379/pd/api/v1/fail/github.com/tikv/pd/pkg/etcdutil/SlowEtcdKVGet

2. simulate pd lost leader
   curl -X PUT -d 'return("2346857576170797299")' http://tc-pd-1.tc-pd-peer.csn-simulator-big-cluster-vd62g.svc:2379/pd/api/v1/fail/github.com/tikv/pd/server/exitCampaignLeader

Before

After

Release note

 add backoff for the reconnect retries in pd-client

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bufferflies
• nolouch

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[bufferflies]

/merge

[ti-chi-bot]

@bufferflies: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

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

Commit hash: 1c3e327

[ti-chi-bot]

@ti-chi-bot: Your PR was out of date, I have automatically updated it for you.

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[bufferflies]

/merge

[ti-chi-bot]

@bufferflies: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

If you have any questions about the PR merge process, please refer to pr process.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[bufferflies]

//run-test retry=5

[bufferflies]

/run-test retry=5

[nolouch]

/test retry=5

[nolouch]

/test