25d99cd25 Use software renderer in embedder unittests (flutter/engine#6928) (#24749)

https://github.com/flutter/engine/compare/99e73d8c64ed...25d99cd25780

git log 99e73d8c64ed..25d99cd25780 --no-merges --oneline
25d99cd25 Use software renderer in embedder unittests (flutter/engine#6928)


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bin/internal/engine.version

-99e73d8c64ed3ebefd90cd339f268b819660932e
+25d99cd25780e7f692cd44a0c34fcd3aa2600ab4