id: fix the id allocator is not monotonic (#3305)

[ti-srebot]

cherry-pick #3305 to release-4.0

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What problem does this PR solve?

What is changed and how it works?

This PR tries to make the id monotonic since there are many components that depend on this property. ref: #3303

Check List

Tests

• Unit test

Related changes

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

Release note

[ti-srebot]

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

[codecov]

Codecov Report

Merging #3308 (bea1a62) into release-4.0 (703471b) will increase coverage by 0.36%.
The diff coverage is 38.46%.

@@               Coverage Diff               @@
##           release-4.0    #3308      +/-   ##
===============================================
+ Coverage        74.77%   75.13%   +0.36%     
===============================================
  Files              209      209              
  Lines            19594    19599       +5     
===============================================
+ Hits             14651    14726      +75     
+ Misses            3617     3540      -77     
- Partials          1326     1333       +7     

Flag	Coverage Δ
unittests	75.13% <38.46%> (+0.36%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/server.go	72.80% <0.00%> (-0.87%)	⬇️
server/id/id.go	76.19% <50.00%> (+1.19%)	⬆️
pkg/errs/errs.go	75.00% <0.00%> (-25.00%)	⬇️
server/heartbeat_streams.go	65.93% <0.00%> (-6.60%)	⬇️
server/kv/etcd_kv.go	79.71% <0.00%> (-5.80%)	⬇️
server/config/persist_options.go	87.16% <0.00%> (-0.76%)	⬇️
server/grpc_service.go	59.87% <0.00%> (+0.40%)	⬆️
server/schedule/operator_controller.go	81.71% <0.00%> (+0.58%)	⬆️
server/cluster/coordinator.go	68.18% <0.00%> (+0.80%)	⬆️
... and 5 more

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[nolouch]

lgtm

[nolouch]

/merge

[ti-chi-bot]

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

/run-all-tests

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[ti-chi-bot]

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

Commit hash: bea1a62

[HunDunDM]

This PR contains #3310