Remove usage of CHECK_NOTNULL

We want to switch to absl logging instead of glog.  gtest and ceres are
going there, and we already have absl as a dependency.  ABSL doesn't
have CHECK_NOTNULL, and we can move things over in an easier to review
fashion.

Change-Id: Ifd9a11ec34a2357cec43f88dba015db9c28ed2cf
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/y2024/autonomous/autonomous_actor.cc b/y2024/autonomous/autonomous_actor.cc
index 0f70292..83cf5b1 100644
--- a/y2024/autonomous/autonomous_actor.cc
+++ b/y2024/autonomous/autonomous_actor.cc
@@ -51,8 +51,10 @@
           event_loop
               ->MakeFetcher<::y2024::control_loops::superstructure::Status>(
                   "/superstructure")),
-      robot_constants_(CHECK_NOTNULL(robot_constants)),
-      auto_splines_() {}
+      robot_constants_(robot_constants),
+      auto_splines_() {
+  CHECK(robot_constants_ != nullptr);
+}
 
 void AutonomousActor::Replan() {
   AutonomousMode mode = robot_constants_->common()->autonomous_mode();