Media: Update tidb-architecture.png (#4859)

[ti-srebot]

cherry-pick #4859 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In docs repo:
git pr https://github.com/pingcap/docs/pull/4861

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/docs.git pr/4861:release-5.0-5304d3b33480

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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)

Update tidb-architecture.png

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

• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
• v2.1 (TiDB 2.1 versions)

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

• This PR is translated from: media: update the TiDB architecture image docs-cn#5562
• 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-srebot]

@Joyinqin you're already a collaborator in bot's repo.