android: build: Force all subprojects to use compileSdkVersion 34

Force all subprojects to use compileSdkVersion 34 to resolve
resource linking error during APK release build

Added a `subprojects` block in `android/build.gradle` to ensure all
subprojects are compiled with `compileSdkVersion 34`. This temporary
workaround addresses the `android:attr/lStar` resource linking issue
when building the release APK. The block is placed before the existing
`subprojects` configuration to avoid evaluation errors.

flutter/flutter#153281 (comment)

src/ui/flutter_app/android/build.gradle

@@ -6,6 +6,16 @@ allprojects {
 }
 
 rootProject.buildDir = '../build'
+subprojects {
+    afterEvaluate { project ->
+        if (project.plugins.hasPlugin("com.android.application") ||
+                project.plugins.hasPlugin("com.android.library")) {
+            project.android {
+                compileSdkVersion 34
+            }
+        }
+    }
+}
 subprojects {
     project.buildDir = "${rootProject.buildDir}/${project.name}"
     project.evaluationDependsOn(':app')