Added minHeight to profiler flamegraphs (elastic#210443)

## Summary
Solves elastic/prodfiler#4896

This PR set a minimum height of 400px to flamegraph charts in universal
profiling.

below shows the flamegraphs at their minimum heights.

<img width="860" alt="Screenshot 2025-02-10 at 10 24 02"
src="https://github.com/user-attachments/assets/ad121d44-da47-46a5-a719-08b59fee74c4"
/>
<img width="1040" alt="Screenshot 2025-02-10 at 10 24 22"
src="https://github.com/user-attachments/assets/feb07704-74a1-4eab-ab29-0bac59944296"
/>

### Checklist

Check the PR satisfies following conditions. 

Reviewers should verify this PR satisfies this list as well.

- [x] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

x-pack/solutions/observability/plugins/profiling/public/components/flamegraph/index.tsx

@@ -137,7 +137,7 @@ export function FlameGraph({
         <EuiFlexItem>
           <EuiFlexGroup direction="row">
             {columnarData.viewModel.label.length > 0 && (
-              <EuiFlexItem grow>
+              <EuiFlexItem grow style={{ minHeight: '400px' }}>
                 <Chart key={columnarData.key}>
                   <Settings
                     theme={chartTheme}