Bug 1849833 - Replace deprecated compileSdkVersion.

This is replaced by defaultConfig compileSdk.

app/build.gradle

@@ -23,8 +23,6 @@ import static org.gradle.api.tasks.testing.TestResult.ResultType
 apply from: 'benchmark.gradle'
 
 android {
-    compileSdkVersion config.compileSdkVersion
-
     project.maybeConfigForJetpackBenchmark(it)
     if (project.hasProperty("testBuildType")) {
         // Allowing to configure the test build type via command line flag (./gradlew -PtestBuildType=beta ..)
@@ -35,6 +33,7 @@ android {
     defaultConfig {
         applicationId "org.mozilla"
         minSdkVersion config.minSdkVersion
+        compileSdk config.compileSdkVersion
         targetSdkVersion config.targetSdkVersion
         versionCode 1
         versionName Config.generateDebugVersionName()