Convert last user of Time.format() to an alt.

Convert last frameworks/base/ user of
android.text.format.Time.format("%Y-%m-%d %H:%M:%S")
to use calculations based on java.time instead. This avoids future
Y2038 issues associated with Time.

Bug: 16550209
Test: build / boot / treehugger
Change-Id: I3843450350c26505211a2788c4ed114e30403fa8
diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index a3ab27e..7267da0 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -211,7 +211,7 @@
 import android.sysprop.DisplayProperties;
 import android.telecom.TelecomManager;
 import android.text.TextUtils;
-import android.text.format.Time;
+import android.text.format.TimeMigrationUtils;
 import android.util.ArrayMap;
 import android.util.EventLog;
 import android.util.Log;
@@ -5878,9 +5878,9 @@
                 tracesFile = File.createTempFile("app_slow", null, tracesDir);
 
                 StringBuilder sb = new StringBuilder();
-                Time tobj = new Time();
-                tobj.set(System.currentTimeMillis());
-                sb.append(tobj.format("%Y-%m-%d %H:%M:%S"));
+                String timeString =
+                        TimeMigrationUtils.formatMillisWithFixedFormat(System.currentTimeMillis());
+                sb.append(timeString);
                 sb.append(": ");
                 TimeUtils.formatDuration(SystemClock.uptimeMillis()-startTime, sb);
                 sb.append(" since ");