init: move exec operations out of ServiceManager

These can be implemented without ServiceManager, so we remove them and
make ServiceManager slightly less of a God class.

Test: boot bullhead
Test: init unit tests
Change-Id: Ia6e546fe5292255412245256f7d230af4ece135f
diff --git a/init/init.cpp b/init/init.cpp
index 03f0bb7..a12afae 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -1180,10 +1180,10 @@
         // By default, sleep until something happens.
         int epoll_timeout_ms = -1;
 
-        if (!(waiting_for_prop || sm.IsWaitingForExec())) {
+        if (!(waiting_for_prop || Service::is_exec_service_running())) {
             am.ExecuteOneCommand();
         }
-        if (!(waiting_for_prop || sm.IsWaitingForExec())) {
+        if (!(waiting_for_prop || Service::is_exec_service_running())) {
             if (!shutting_down) {
                 auto next_process_restart_time = RestartProcesses();