gomod: update pdclient to support backoff mechanism for memberLoop (#46769)

[ti-chi-bot]

This is an automated cherry-pick of #46769

Signed-off-by: husharp jinhao.hu@pingcap.com<!--

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What problem does this PR solve?

Issue Number: close #46770, ref tikv/pd#6556

Problem Summary:

• Add backoff mechanism
  When waiting for the goroutine to update, the expo function can be used to backoff to sleep when an error is encountered.

PR Summary

Add backoff mechanism

• When waiting for the goroutine to update, the expo function can be used to backoff to sleep when an error is encountered.

Reproduce Step

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

Reproduce Result

Grpc request GetMember keeps high:

TiKV side show

PR Effect

The Grpc GetMember call was reduced from 3.2k to 170, which is relative to the TiDB numbers and client requests for triaging checkLeader.

For 20 * tidb 3 * PD 50 * TiKV
170 = (50 * 3 / 3 / 3[TiKV side] + 20 * 2 [TiDB side]) * 3[PD Num]

And more tests are necessary to ensure that no further issues arise.

What is changed and how it works?

Check List

test by pd
Tests

• Unit test
• Integration test

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

update pdclient to support backoff mechanism for memberLoop

[nolouch]

cc @HuSharp

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.1@4007579). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.1     #46955   +/-   ##
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  Coverage               ?   73.4658%           
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  Files                  ?       1203           
  Lines                  ?     376756           
  Branches               ?          0           
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  Hits                   ?     276787           
  Misses                 ?      82315           
  Partials               ?      17654           

[HuSharp]

updated by https://github.com/tikv/pd/commits/release-7.1

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-09-18 08:31:51.482769824 +0000 UTC m=+506277.450357871: ☑️ agreed by nolouch.
• 2023-09-18 08:35:05.292993209 +0000 UTC m=+506471.260581260: ☑️ agreed by rleungx.

[ti-chi-bot]

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CabinfeverB, nolouch, rleungx, xhebox

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