Align max --dml-batch-size with the implementation

[yktakaha4]

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Related issue: None

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Description

This PR updates the upper limit of the --dml-batch-size flag from 100 to 1000 to match the actual implementation.

The upper limit of --dml-batch-size has not changed since 2017.

ref: #438

gh-ost/go/base/context.go

Lines 645 to 652 in 7c3b9a1

	func (this *MigrationContext) SetDMLBatchSize(batchSize int64) {
	if batchSize < 1 {
	batchSize = 1
	}
	if batchSize > MaxEventsBatchSize {
	batchSize = MaxEventsBatchSize
	}
	atomic.StoreInt64(&this.DMLBatchSize, batchSize)

gh-ost/go/base/context.go

Line 54 in 7c3b9a1

MaxEventsBatchSize = 1000

In case this PR introduced Go code changes:

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.

[Copilot]

Pull Request Overview

This PR updates the upper limit of the --dml-batch-size flag from 100 to 1000 to align the documentation and command-line help text with the actual implementation, which has supported up to 1000 since 2017.

• Updated the command-line flag description in main.go to reflect the correct upper limit
• Updated the documentation to match the implementation's actual supported range

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
go/cmd/gh-ost/main.go	Updated dml-batch-size flag description to show correct range (1-1000)
doc/command-line-flags.md	Updated documentation to reflect the actual supported range for dml-batch-size