Fix invisible scroll bar on release pipeline logs

[Wedgetable]

To see an example of the issue: click on the dotnet stage FlexLogger_Tests_Execution_Group2 task here. Notice that the area where a scrollbar should be is just black:

With these changes, there is now a visible scrollbar you can interact with:

Tested: ✅ Version is incremented following semantic versioning ✅ Runs in latest stable Chrome and Firefox without Javascript errors (also tested Edge) ✅ Works in both dev.azure.com/ni and ni.visualstudio.com ✅ Customizations work in both light and dark theme ✅ Does not report any issues in eslint (run npm run build)

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