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/data/library/LibraryUpdateService.kt

@@ -177,8 +177,6 @@ class LibraryUpdateService(
      * the wake lock.
      */
     override fun onCreate() {
-        super.onCreate()
-
         notifier = LibraryUpdateNotifier(this)
         wakeLock = acquireWakeLock(javaClass.name)
 
@@ -198,7 +196,6 @@ class LibraryUpdateService(
         if (instance == this) {
             instance = null
         }
-        super.onDestroy()
     }
 
     /**