[Impeller] enable OpenGL fallback on Android. (#56591)

Ship impeller OpenGLES on non-vulkan android devices

Fixes https://github.com/flutter/flutter/issues/158361

shell/platform/android/flutter_main.cc

diff --git a/shell/platform/android/flutter_main.cc b/shell/platform/android/flutter_main.cc
index 184a2e9..4159d37 100644
--- a/shell/platform/android/flutter_main.cc
+++ b/shell/platform/android/flutter_main.cc
@@ -240,7 +240,7 @@
     return AndroidRenderingAPI::kSoftware;
   }
   constexpr AndroidRenderingAPI kVulkanUnsupportedFallback =
-      AndroidRenderingAPI::kSkiaOpenGLES;
+      AndroidRenderingAPI::kImpellerOpenGLES;
 
   // Debug/Profile only functionality for testing a specific
   // backend configuration.

shell/platform/android/platform_view_android_unittests.cc

diff --git a/shell/platform/android/platform_view_android_unittests.cc b/shell/platform/android/platform_view_android_unittests.cc
index 3d7ed4f..fc1c2d9 100644
--- a/shell/platform/android/platform_view_android_unittests.cc
+++ b/shell/platform/android/platform_view_android_unittests.cc
@@ -22,7 +22,7 @@
               AndroidRenderingAPI::kImpellerVulkan);
   } else {
     EXPECT_EQ(FlutterMain::SelectedRenderingAPI(settings),
-              AndroidRenderingAPI::kSkiaOpenGLES);
+              AndroidRenderingAPI::kImpellerOpenGLES);
   }
 }