Some dashboard charts intermittently fall back to color_scheme instead of label_colors on initial render

### Bug description

When using `label_colors` in dashboard JSON metadata, some charts intermittently do not apply the defined colors in "label_colors" and instead fall back to the chart's default `color_scheme` on initial render.

This issue does not affect all charts consistently:
- Most of the charts correctly apply `label_colors`
- Some charts (often the first one) fall back to the default color scheme
- The behavior is highly intermittent and not reproducible on every page load

---

### Observed behavior

- Only some charts are affected, while others display correct colors
- After user interaction (e.g. clicking legend or refreshing the page), the colors become correct

---

### Expected behavior

All charts should consistently apply the `label_colors` defined in dashboard metadata on initial render.

---

### Dashboard label_colors configuration

The dashboard uses the following `label_colors` configuration:

```json
{
"label_colors": {
"60_Crashed": "#8b0000",
"50_Error": "#ff0000",
"40_Failed": "#ff8c00",
"30_Undefined": "#ffd700",
"20_Passed": "#008000",
"10_Executed": "#0000ff",
"01_Invalid": "#ff00ff",
"00_NoResult": "#808080"
}
}
```
Dashboard-level color_scheme is empty, the charts use "supersetColors" as color_scheme.

---

### Screenshots/recordings

The following screenshot shows the case when the issue occurs

After refreshing or clicking legend, the colors become correct

---
### Superset version

6.0.0

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### Python version

I don't know

### Node version

I don't know

### Browser

Chrome

### Additional context

I have reviewed similar issues related to color assignment and dashboard behavior (e.g. #36406), but I could not find a case fully matching this behavior (intermittent fallback to `color_scheme` with `label_colors` defined).

Based on the observed behavior, it seems likely that this is related to rendering order or timing in the frontend. However, this is only a hypothesis.

I would appreciate confirmation from maintainers whether this is an expected limitation, a known issue, or a bug in the current rendering pipeline. Thanks.
``

### Checklist

- [x] I have searched Superset docs and Slack and didn't find a solution to my problem.
- [x] I have searched the GitHub issue tracker and didn't find a similar bug report.
- [x] I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

No source files or tests are named. Start by reproducing the dashboard's initial render with the provided label_colors configuration, then trace how chart colors are resolved before and after legend interaction. Done means every chart applies label_colors consistently on its first render, with a regression test for the intermittent fallback.

Written by the indexing model from the issue text.