X11 flakiness in CI test runs

[dweymouth]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

An intermittent bug with the locale parsing is causing many CI tests to be unreliable, making CI a much less useful signal of correctness in PRs

 2025/01/01 17:32:55 Fyne error:  Error parsing user locale C
2025/01/01 17:32:55   Cause: language: tag is not well-formed
2025/01/01 17:32:55   At: /home/runner/work/fyne/fyne/lang/locale.go:35
X Error of failed request:  BadAccess (attempt to access private resource denied)
  Major opcode of failed request:  150 (GLX)
  Minor opcode of failed request:  5 (X_GLXMakeCurrent)
  Serial number of failed request:  459
  Current serial number in output stream:  459
FAIL	fyne.io/fyne/v2/internal/driver/glfw	1.794s

How to reproduce

look at test failures of many open PRs

Screenshots

No response

Example code

n/a

Fyne version

develop

Go compiler version

n/a

Operating system and version

n/a

Additional Information

No response

[andydotxyz]

The locale failure does not cause the X11 error, it is a side-effect of a threading change which has been fixed on all testing machines but is still somehow happening on the AWS node.