ebs br: resume gc and scheduler when volume snapshots created (#5288)

[ti-chi-bot]

This is an automated cherry-pick of #5288

What problem does this PR solve?

1. resume gc and pd scheduler when all the volume snapshots are created
   Closes ebs br: shrink the window of pause gc and schedule during backup #5256

2. send SIGTERM to the BR process when tidb-backup-manager receives SIGTERM

3. read stderr async in case that the pipe of stderr is full and blocks the BR process
   Closes backup job is stuck(snapshot is completed) #5281

4. The EBS backup task may cause the import task to fail
   Closes The EBS backup task may cause the import task to fail #5282

What is changed and how does it work?

data plane:

1. check if the backupmeta file is existed when the backup enter execute phase. if it is existed, modify backup status VolumeBackupSnapshotsCreated

control plane:
2. if all the backups in data plane has status VolumeBackupSnapshotsCreated, modify resumeGcSchedule field true in the backup that is responsible to pause gc and pd schduler.

data plane:
3. if resumeGcSchedule field is true, delete the initialize pod and modify backup status VolumeBackupInitializeComplete

control plane:
5. if the backup with resumeGcSchedule: true has status VolumeBackupInitializeComplete, modify volume backup status SnapshotsCreated. It means all the volume snapshots are created and gc and pd schedulers are resumed.

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

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[codecov-commenter]

Codecov Report

Merging #5298 (1d93d0a) into release-1.5 (d5d4b38) will increase coverage by 2.70%.
Report is 1 commits behind head on release-1.5.
The diff coverage is 39.50%.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.5    #5298      +/-   ##
===============================================
+ Coverage        57.53%   60.24%   +2.70%     
===============================================
  Files              251      258       +7     
  Lines            30210    34238    +4028     
===============================================
+ Hits             17382    20626    +3244     
- Misses           11122    11749     +627     
- Partials          1706     1863     +157     

Flag	Coverage Δ
e2e	27.76% <4.76%> (?)
unittest	57.48% <41.75%> (-0.06%)	⬇️

[BornChanger]

/retest