Fix ForegroundServiceDidNotStartInTimeException (#6470)

* Start the `FetchPushForegroundService ` in foreground ASAP. This is a first step to mitigate `ForegroundServiceDidNotStartInTimeException` being thrown.

* Don't stop the service immediately if it's running but not in foreground. Try waiting up to 5s for it to be in foreground.

libraries/push/test/src/main/kotlin/io/element/android/libraries/push/test/push/FakePushHandlingWakeLock.kt

@@ -18,7 +18,7 @@ class FakePushHandlingWakeLock(
         lock.invoke(time)
     }
 
-    override fun unlock() {
+    override suspend fun unlock() {
         unlock.invoke()
     }
 }