Fix side effects of trace-ipc and dumpheap commands

These shell commands were implicitly deleting any client-named file for
which the system uid had deletion capability.  They no longer do this,
instead using only the client's own capabilities and file manipulation
modes.

Bug: 185398942
Test: manual "adb shell cmd activity dumpheap system_server /data/system/last-fstrim"
Test: atest CtsPermissionTestCases:ShellCommandPermissionTest
Change-Id: Ie61ab2c3f4bfbd04de09ca99c1116d1129461e8f
(cherry picked from commit 76e8e04703cb49a4984145a18f4552c4bcf72172)

services/core/java/com/android/server/am/ActivityManagerShellCommand.java

diff --git a/services/core/java/com/android/server/am/ActivityManagerShellCommand.java b/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
index 149e3ba..122af56 100644
--- a/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
+++ b/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
@@ -94,7 +94,6 @@
 import com.android.server.compat.PlatformCompat;
 
 import java.io.BufferedReader;
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
@@ -787,8 +786,7 @@
             return -1;
         }
 
-        File file = new File(filename);
-        file.delete();
+        // Writes an error message to stderr on failure
         ParcelFileDescriptor fd = openFileForSystem(filename, "w");
         if (fd == null) {
             return -1;
@@ -942,16 +940,16 @@
             String logNameTimeString = LOG_NAME_TIME_FORMATTER.format(localDateTime);
             heapFile = "/data/local/tmp/heapdump-" + logNameTimeString + ".prof";
         }
-        pw.println("File: " + heapFile);
-        pw.flush();
 
-        File file = new File(heapFile);
-        file.delete();
+        // Writes an error message to stderr on failure
         ParcelFileDescriptor fd = openFileForSystem(heapFile, "w");
         if (fd == null) {
             return -1;
         }
 
+        pw.println("File: " + heapFile);
+        pw.flush();
+
         final CountDownLatch latch = new CountDownLatch(1);
 
         final RemoteCallback finishCallback = new RemoteCallback(new OnResultListener() {