Bug 1807307 - Disable LeakCanary in ui-test-apk with gradle flag

app/build.gradle

@@ -444,6 +444,23 @@ android.applicationVariants.configureEach { variant ->
         buildConfigField 'String', 'POCKET_CONSUMER_KEY', '""'
         println("--")
     }
+
+// -------------------------------------------------------------------------------------------------
+// BuildConfig: Set flag to disable LeakCanary in debug (on CI builds)
+// -------------------------------------------------------------------------------------------------
+
+    if (isDebug) {
+        if (project.hasProperty("disableLeakCanary") || gradle.hasProperty("localProperties.disableLeakCanary")) {
+            buildConfigField "boolean", "LEAKCANARY", "false"
+            println("LeakCanary enabled in debug: false")
+        } else {
+            buildConfigField "boolean", "LEAKCANARY", "true"
+            println("LeakCanary enabled in debug: true")
+        }
+    } else {
+        buildConfigField "boolean", "LEAKCANARY", "false"
+    }
+
 }
 
 // Generate Kotlin code for the Fenix Glean metrics.

app/src/androidTest/java/org/mozilla/fenix/ui/SettingsAdvancedTest.kt

@@ -71,7 +71,9 @@ class SettingsAdvancedTest {
             verifyExternalDownloadManagerButton()
             verifyExternalDownloadManagerToggle(false)
             verifyLeakCanaryButton()
-            verifyLeakCanaryToggle(true)
+            // LeakCanary is disabled in UI tests.
+            // See BuildConfig.LEAKCANARY.
+            verifyLeakCanaryToggle(false)
             verifyRemoteDebuggingButton()
             verifyRemoteDebuggingToggle(false)
         }

app/src/debug/java/org/mozilla/fenix/DebugFenixApplication.kt

@@ -23,7 +23,7 @@ class DebugFenixApplication : FenixApplication() {
 
         val isEnabled = components.strictMode.resetAfter(StrictMode.allowThreadDiskReads()) {
             PreferenceManager.getDefaultSharedPreferences(this)
-                .getBoolean(getPreferenceKey(R.string.pref_key_leakcanary), true)
+                .getBoolean(getPreferenceKey(R.string.pref_key_leakcanary), BuildConfig.LEAKCANARY)
         }
 
         updateLeakCanaryState(isEnabled)

app/src/main/res/xml/preferences.xml

@@ -166,7 +166,6 @@
             android:title="@string/preferences_external_download_manager" />
 
         <androidx.preference.SwitchPreference
-            android:defaultValue="true"
             android:key="@string/pref_key_leakcanary"
             android:title="@string/preference_leakcanary"
             app:iconSpaceReserved="false"