metrics(ticdc): add kafka compression ratio description for grafana

[sdojjy]

What problem does this PR solve?

Issue Number: close #11347

What is changed and how it works?

add kafka compression ratio description for grafana

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3AceShowHand, asddongmen

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

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [3AceShowHand,asddongmen]

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]

[LGTM Timeline notifier]

Timeline:

• 2024-06-26 07:36:43.843256601 +0000 UTC m=+791530.328745435: ☑️ agreed by 3AceShowHand.
• 2024-06-26 07:38:13.392035974 +0000 UTC m=+791619.877524806: ☑️ agreed by asddongmen.

[sdojjy]

/retest-required

[sdojjy]

/retest-required

[sdojjy]

/retest-required

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.6426%. Comparing base (a2e6219) to head (d2918fd).

Additional details and impacted files

Components	Coverage Δ
cdc	61.4595% <ø> (+0.0304%)	⬆️
dm	51.1990% <ø> (-0.0283%)	⬇️
engine	63.4091% <ø> (+0.0352%)	⬆️

Flag	Coverage Δ
unit	57.6426% <ø> (+0.0079%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master     #11348        +/-   ##
================================================
+ Coverage   57.6347%   57.6426%   +0.0079%     
================================================
  Files           849        849                
  Lines        126160     126160                
================================================
+ Hits          72712      72722        +10     
+ Misses        48048      48038        -10     
  Partials       5400       5400                

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #11352.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #11353.