v7.5 - gc cpu monitoring indicators are not displayed

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

TIDB-Runtime --> CPU USage --> Only cpu-usage+ cpu limit ;

gc cpu monitoring indicators are not displayed

### 2. What did you expect to see? (Required)

TIDB-Runtime --> CPU USage --> cpu-usage+ gc cpu usage + cpu limit ;

### 3. What did you see instead (Required)

TIDB-Runtime --> CPU USage --> Only cpu-usage+ cpu limit ;

### 4. What is your TiDB version? (Required)

V7.5.0

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| tidb_version() |
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| Release Version: v7.5.0
Edition: Community
Git Commit Hash: 069631e2ecfedc000ffb92c67207bea81380f020
Git Branch: heads/refs/tags/v7.5.0
UTC Build Time: 2023-11-24 08:50:14
GoVersion: go1.21.3
Race Enabled: false
Check Table Before Drop: false
Store: tikv |
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