Fix infinite content observer issue

Signed-off-by: Jonas Mayer <jonas.a.mayer@gmx.net>

app/src/androidTest/java/com/nextcloud/client/jobs/BackgroundJobManagerTest.kt

@@ -201,7 +201,7 @@ class BackgroundJobManagerTest {
         fun job_is_unique_and_replaces_previous_job() {
             verify(workManager).enqueueUniqueWork(
                 eq(BackgroundJobManagerImpl.JOB_CONTENT_OBSERVER),
-                eq(ExistingWorkPolicy.APPEND),
+                eq(ExistingWorkPolicy.REPLACE),
                 argThat(IsOneTimeWorkRequest())
             )
         }

app/src/main/java/com/nextcloud/client/jobs/BackgroundJobManagerImpl.kt

@@ -264,7 +264,7 @@ internal class BackgroundJobManagerImpl(
             .setConstraints(constrains)
             .build()
 
-        workManager.enqueueUniqueWork(JOB_CONTENT_OBSERVER, ExistingWorkPolicy.APPEND, request)
+        workManager.enqueueUniqueWork(JOB_CONTENT_OBSERVER, ExistingWorkPolicy.REPLACE, request)
     }
 
     override fun schedulePeriodicContactsBackup(user: User) {