Redo the Android aab signing again

.gitignore

@@ -54,7 +54,9 @@ android/log.bck
 /ios/ouisync/build-dir/
 .vscode/settings.json
 
-# Keystore secrets (we used to have it here, but then moved all the secrets to secrets/)
+# Keystore secrets (we used to have it here, but then moved all the secrets to
+# secrets/). Now it is a symbolic link to secrets/android/key.properties, but
+# we still don't want to commit it.
 android/key.properties
 
 # Whatever secrets needed to build a release for any of the supported platform.

android/app/build.gradle

@@ -22,7 +22,7 @@ if (flutterVersionName == null) {
 }
 
 def keystoreProperties = new Properties()
-def keystorePropertiesFile = rootProject.file('key.properties')
+def keystorePropertiesFile = rootProject.file('../secrets/android/key.properties')
 if (keystorePropertiesFile.exists()) {
     keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
 }
@@ -87,8 +87,9 @@ android {
 
     buildTypes {
         release {
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            if (System.getenv("NO_SIGN") != "true") {
+            if (keystorePropertiesFile.exists()) {
+                signingConfig signingConfigs.release
+            } else {
                 signingConfig signingConfigs.debug
             }
         }

util/release.dart

@@ -508,9 +508,7 @@ Future<File> buildAab(BuildDesc buildDesc) async {
     buildDesc.version.build[0].toString(),
     '--build-name',
     buildDesc.toString(),
-  ], environment: {
-    "NO_SIGN": "true"
-  });
+  ]);
 
   return File(inputPath);
 }
@@ -824,10 +822,9 @@ Future<Directory> createOutputDir(BuildDesc buildDesc) async {
 
 Future<void> run(
   String command,
-  List<String> args, {
+  List<String> args, [
   String? workingDirectory,
-  Map<String, String>? environment,
-}) async {
+]) async {
   final process = await Process.start(
     command,
     args,