Fix typo.

Bug: 299329948
Change-Id: If1f6ef1a950ee93c2cb4413205c87a9454734573
Test: N/A

apex/jobscheduler/service/aconfig/job.aconfig

@@ -2,7 +2,7 @@ package: "com.android.server.job"
 
 flag {
     name: "relax_prefetch_connectivity_constraint_only_on_charger"
-    namespace: "backstagepower"
+    namespace: "backstage_power"
     description: "Only relax a prefetch job's connectivity constraint when the device is charging"
     bug: "299329948"
 }
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