Use 'cmd activity' instead 'am' to send a broadcast.

'am' is a deprecated binary that calls the ActivityManager shell
command behind the scenes, so calling 'cmd activity' directly
eliminates a process fork.

Bug: 34833915
Test: manual verification

Change-Id: Ia156897d784aa1d64f60317f92828987d64936e3
diff --git a/cmds/dumpstate/utils.cpp b/cmds/dumpstate/utils.cpp
index c6dfa37..0fc2bce 100644
--- a/cmds/dumpstate/utils.cpp
+++ b/cmds/dumpstate/utils.cpp
@@ -711,7 +711,8 @@
 }
 
 void send_broadcast(const std::string& action, const std::vector<std::string>& args) {
-    std::vector<std::string> am = {"/system/bin/am", "broadcast", "--user", "0", "-a", action};
+    std::vector<std::string> am = {
+        "/system/bin/cmd", "activity", "broadcast", "--user", "0", "-a", action};
 
     am.insert(am.end(), args.begin(), args.end());