v1.12.13+hotfix.5 cherry-picks (#46726)

* flutter/engine@2994f7e v1.12.13+hotfix.5 cherry-picks
  * flutter/engine@57afd86 Remove specificity on Android and iOS
  * flutter/engine@253851e Move Fuchsia unit test runners into engine repo
diff --git a/bin/internal/engine.version b/bin/internal/engine.version
index e3574c1..cf062e0 100644
--- a/bin/internal/engine.version
+++ b/bin/internal/engine.version
@@ -1 +1 @@
-ac9391978e7c0693b75a82c219e059b6ffee35c4
+2994f7e1e682039464cb25e31a78b86a3c59b695