release notes: remove duplicate notes

[Oreoxmt]

What is changed, added or deleted? (Required)

Which TiDB version(s) do your changes apply to? (Required)

• [dr-autosync] pitr checkpoint ts lag up to 15min after down backup dc  tikv/tikv#15279 and PITR checkpoint lag > 10min during tikv rolling restart tikv/tikv#13638 were fixed in v6.5.4. This PR removes duplicate note in v6.5.5
• Seems region leaders can lose after one tikv instance fail tikv/tikv#14547 was fixed in v6.5.3
  Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v7.5 (TiDB 7.5 versions)
• v7.4 (TiDB 7.4 versions)
• v7.3 (TiDB 7.3 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)
• v5.1 (TiDB 5.1 versions)
• v5.0 (TiDB 5.0 versions)

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

• This PR is translated from: release notes: remove duplicate notes docs-cn#15331
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-10-30 13:23:18.953706391 +0000 UTC m=+2872996.540816536: ☑️ agreed by hfxsd.

[ti-chi-bot]

@hicqu: adding LGTM is restricted to approvers and reviewers in OWNERS files.

Details

In response to this:

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[Oreoxmt]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Oreoxmt

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [Oreoxmt]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #15227.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #15228.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.3: #15229.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.4: #15230.