Closes #2000 - Don't flash LeakCanary setting in release builds (#2006)

app/build.gradle

@@ -31,6 +31,7 @@ android {
         testInstrumentationRunnerArguments clearPackageData: 'true'
         manifestPlaceholders.isRaptorEnabled = "false"
         buildConfigField "boolean", "IS_RELEASED", "false"
+        resValue "bool", "IS_NOT_RELEASED", "true"
     }
 
     def releaseTemplate = {
@@ -53,9 +54,11 @@ android {
         }
         nightly releaseTemplate >> {
             buildConfigField "boolean", "IS_RELEASED", "true"
+            resValue "bool", "IS_NOT_RELEASED", "false"
         }
         beta releaseTemplate >> {
             buildConfigField "boolean", "IS_RELEASED", "true"
+            resValue "bool", "IS_NOT_RELEASED", "false"
         }
     }
 

app/src/main/java/org/mozilla/fenix/settings/SettingsFragment.kt

@@ -198,7 +198,6 @@ class SettingsFragment : PreferenceFragmentCompat(), CoroutineScope, AccountObse
         preferenceMakeDefaultBrowser?.onPreferenceClickListener =
             getClickListenerForMakeDefaultBrowser()
 
-        preferenceLeakCanary?.isVisible = !BuildConfig.IS_RELEASED
         if (!BuildConfig.IS_RELEASED) {
             preferenceLeakCanary?.onPreferenceChangeListener =
                 Preference.OnPreferenceChangeListener { _, newValue ->

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

@@ -58,10 +58,11 @@
             android:key="@string/pref_key_data_choices"
             android:title="@string/preferences_data_choices" />
         <androidx.preference.SwitchPreference
+            android:defaultValue="false"
             android:icon="@drawable/ic_info"
             android:key="@string/pref_key_leakcanary"
             android:title="@string/preference_leakcanary"
-            android:defaultValue="false" />
+            app:isPreferenceVisible="@bool/IS_NOT_RELEASED" />
     </androidx.preference.PreferenceCategory>
 
     <PreferenceCategory