Remove source overwrite logic since built-in sources no longer exist

app/src/main/java/eu/kanade/tachiyomi/extension/ExtensionManager.kt

@@ -124,8 +124,7 @@ class ExtensionManager(
             .map { it.extension }
         installedExtensions
             .flatMap { it.sources }
-            // overwrite is needed until the bundled sources are removed
-            .forEach { sourceManager.registerSource(it, true) }
+            .forEach { sourceManager.registerSource(it) }
 
         untrustedExtensions = extensions
             .filterIsInstance<LoadResult.Untrusted>()

app/src/main/java/eu/kanade/tachiyomi/source/SourceManager.kt

@@ -32,11 +32,11 @@ open class SourceManager(private val context: Context) {
 
     fun getCatalogueSources() = sourcesMap.values.filterIsInstance<CatalogueSource>()
 
-    internal fun registerSource(source: Source, overwrite: Boolean = false) {
-        if (overwrite || !sourcesMap.containsKey(source.id)) {
+    internal fun registerSource(source: Source) {
+        if (!sourcesMap.containsKey(source.id)) {
             sourcesMap[source.id] = source
         }
-        if (overwrite || !stubSourcesMap.containsKey(source.id)) {
+        if (!stubSourcesMap.containsKey(source.id)) {
             stubSourcesMap[source.id] = StubSource(source.id)
         }
     }