fix(ci): Use default NDK on GH runners (#3716)

This should fix the flaky kotlin builds if the NDK is actually
installed.

kotlin/android/app/build.gradle.kts

@@ -44,7 +44,10 @@ android {
 
     namespace = "dev.firezone.android"
     compileSdk = 34
-    ndkVersion = "26.1.10909125"
+
+    // Life is easier if we just match the default NDK on the Ubuntu 22.04 runners
+    // https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2204-Readme.md#android
+    ndkVersion = "25.2.9519653"
 
     defaultConfig {
         applicationId = "dev.firezone.android"