tools: chagen scanregions endkey default limit

[IcePigZDB]

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What is the related PR or file link(s)?

• This PR is translated from: doing
• Other reference link(s):
  • directly code PR: api: set scanregions with endkey default limit as 16 tikv/pd#4674
  • tracking issue: api,pd-ctl: support endKey in ScanRegions http interface tikv/pd#4400

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• Delete files
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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn

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[TomShawn]

Rest LGTM

[TomShawn]

/remove-status LGT1
/status LGT2

[TomShawn]

/merge

[ti-chi-bot]

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

Commit hash: 77421c9

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #8618.