browser(firefox-beta): remove use of `mach create-mach-environment` (#10931)
browser(firefox-beta): remove use of `mach create-mach-environment` (#10931)

This command has been removed and is no longer needed: https://github.com/mozilla/gecko-dev/commit/abeedf3bbdabc32f17e0bee074c4b81eded853f6#diff-080f2a5f770785d46fa3a2404de9430136a5a6c5a4739dab3c47cfbd7421ce79
microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright