en,zh: bump operator to v1.5.1 for release-1.5

[csuzhangxc]

First-time contributors' checklist

• I've signed Contributor License Agreement that's required for repo owners to accept my contribution.

What is changed, added, or deleted? (Required)

find . -type f | xargs sed -i "s/v1.5.0/v1.5.1/g"
git checkout -- zh/releases en/releases
git checkout -- zh/whats-new-in-v1.5.md en/whats-new-in-v1.5.md

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

• master (the latest development version)
• v1.5 (TiDB Operator 1.5 versions)
• v1.4 (TiDB Operator 1.4 versions)
• v1.3 (TiDB Operator 1.3 versions)
• v1.2 (TiDB Operator 1.2 versions)

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

• This PR is translated from:
• Other reference link(s):

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-10-19 06:53:42.042164416 +0000 UTC m=+1899219.629274557: ☑️ agreed by ran-huang.

[ran-huang]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ran-huang

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