Misc Service cleanup (#9005)

* Simplify DownloadService wake lock handling

_isRunning is only modified in onCreate/onDestroy, so the listener
job is redundant.

* Drop superclass calls to Service.onCreate/onDestroy

From https://developer.android.com/guide/components/services
> Note: Unlike the activity lifecycle callback methods, you are not
> required to call the superclass implementation of these callback
> methods.

app/src/main/java/eu/kanade/tachiyomi/extension/util/ExtensionInstallService.kt

@@ -22,7 +22,6 @@ class ExtensionInstallService : Service() {
     private var installer: Installer? = null
 
     override fun onCreate() {
-        super.onCreate()
         val notification = notificationBuilder(Notifications.CHANNEL_EXTENSIONS_UPDATE) {
             setSmallIcon(R.drawable.ic_tachi)
             setAutoCancel(false)
@@ -59,7 +58,6 @@ class ExtensionInstallService : Service() {
     }
 
     override fun onDestroy() {
-        super.onDestroy()
         installer?.onDestroy()
         installer = null
     }