[GTK] Lots of GTK3 test runs hanging at potentially the same point

[jonahgraham]

I see regular runs that hang on GitHub actions and the last line of output is:

[INFO] Running org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_BusyIndicator

Such as https://github.com/eclipse-platform/eclipse.platform.swt/actions/runs/20100393887/job/57669450861?pr=2871

If we see this enough I will look into it more. For now this issue is used to track so I know how significant this problem really is.