Update directory for proc stats puller

This puller was migrated to StatsPullAtomService, so a
more appropriate name was chosen.

Bug: 148402814
Test: adb shell cmd stats pull-source 10029
Test: adb shell cmd stats pull-source 10034
Change-Id: I1998bbffa9e32ee0bff5a9a59875c616dafee0f5

services/core/java/com/android/server/stats/pull/StatsPullAtomService.java

@@ -435,8 +435,7 @@ public class StatsPullAtomService extends SystemService {
         mStoragedUidIoStatsReader = new StoragedUidIoStatsReader();
 
         // Initialize PROC_STATS
-        // TODO (b/148402814): Change this directory to stats_pull.
-        mBaseDir = new File(SystemServiceManager.ensureSystemDir(), "stats_companion");
+        mBaseDir = new File(SystemServiceManager.ensureSystemDir(), "stats_pull");
 
         // Disables throttler on CPU time readers.
         mCpuUidUserSysTimeReader = new KernelCpuUidUserSysTimeReader(false);