domain: release server id by revoke etcd session

[AmoebaProtozoa]

What problem does this PR solve?

Issue Number: close #64191

Problem Summary:

What changed and how does it work?

change the way server id was released. Instead of deleting the etcd key directly, which may leak empty lease, close the serverID session instead.

Check List

Tests

• Manual test (add detailed scripts or steps below)

• tiup playground with local build tiup playground --db.binpath ./bin/tidb-server
• check server id and lease

# log
[2025/10/30 15:46:46.044 +08:00] [INFO] [domain.go:2678] [acquireServerID] [serverID=1989] ["lease id"=22319a34154c819a]`

# etcdctl
❯ etcdctl --endpoints 127.0.0.1:2379 get "/tidb/server_id/1989" --prefix -w fields
"ClusterID" : 15674009460217235928
"MemberID" : 3474484975246189105
"Revision" : 298
"RaftTerm" : 2
"Key" : "/tidb/server_id/1989"
"CreateRevision" : 207
"ModRevision" : 207
"Version" : 1
"Value" : "0"
"Lease" : 2463920019634684314
"More" : false
"Count" : 1
❯ etcdctl --endpoints 127.0.0.1:2379 lease timetolive 22319a34154c819a
lease 22319a34154c819a granted with TTL(43200s), remaining(43011s)

• scale-in tidb tiup playground --pid xxx
• check key and lease removed

# log
[2025/10/30 15:51:10.393 +08:00] [INFO] [domain.go:2703] ["releaseServerID succeed"] [serverID=1989] [leaseID=2463920019634684314]

# etcdctl
❯ etcdctl --endpoints 127.0.0.1:2379 get "/tidb/server_id/1989" --prefix -w fields
"ClusterID" : 15674009460217235928
"MemberID" : 3474484975246189105
"Revision" : 366
"RaftTerm" : 2
"More" : false
"Count" : 0
❯ etcdctl --endpoints 127.0.0.1:2379 lease timetolive 22319a34154c819a
lease 22319a34154c819a already expired

Release note

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[tiprow]

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.5263%. Comparing base (0230916) to head (8a38ec6).
⚠️ Report is 21 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #64192        +/-   ##
================================================
+ Coverage   72.6828%   75.5263%   +2.8434%     
================================================
  Files          1858       1882        +24     
  Lines        502725     519170     +16445     
================================================
+ Hits         365395     392110     +26715     
+ Misses       115087     103621     -11466     
- Partials      22243      23439      +1196     

Flag	Coverage Δ
integration	48.9828% <0.0000%> (?)
unit	73.1634% <50.0000%> (+0.9169%)	⬆️

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Components	Coverage Δ
dumpling	52.8700% <ø> (ø)
parser	∅ <ø> (∅)
br	63.9418% <ø> (+17.6046%)	⬆️

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-10-30 07:58:33.163479679 +0000 UTC m=+1549819.240732239: ☑️ agreed by hawkingrei.
• 2025-10-30 08:20:10.267672507 +0000 UTC m=+1551116.344925057: ☑️ agreed by disksing.

[AmoebaProtozoa]

/assign @wjhuang2016

[lance6716]

ptal @wjhuang2016

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: disksing, hawkingrei, wjhuang2016

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[hawkingrei]

/retest