Enable the Event cache by default.

Note that it will not enable it if the user has explicitly disabled it.

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -165,7 +165,7 @@ enum class FeatureFlags(
         key = "feature.event_cache",
         title = "Use SDK Event cache",
         description = "Warning: you must kill and restart the app for the change to take effect.",
-        defaultValue = { false },
+        defaultValue = { true },
         isFinished = false,
     ),
 }