Apply misc TERN

Marlin/src/gcode/calibrate/G28.cpp

 
       if (doZ) {
         TERN_(BLTOUCH, bltouch.init());
-        #if ENABLED(Z_SAFE_HOMING)
-          home_z_safely();
-        #else
-          homeaxis(Z_AXIS);
-        #endif
+
+        TERN(Z_SAFE_HOMING, home_z_safely(), homeaxis(Z_AXIS));
 
         #if HOMING_Z_WITH_PROBE && defined(Z_AFTER_PROBING)
           #if Z_AFTER_HOMING > Z_AFTER_PROBING

Marlin/src/module/temperature.cpp

 
     #else // No PID enabled
 
-      #if HEATER_IDLE_HANDLER
-        const bool is_idling = hotend_idle[ee].timed_out;
-      #else
-        constexpr bool is_idling = false;
-      #endif
+      const bool is_idling = TERN0(HEATER_IDLE_HANDLER, hotend_idle[ee].timed_out);
       const float pid_output = (!is_idling && temp_hotend[ee].celsius < temp_hotend[ee].target) ? BANG_MAX : 0;
 
     #endif