PSS1 fixes

Dear @benjaminbertrand , could you please merge this? Thanks!

NON-APPROVED/pss1-pss/embedded_displays/diagnostics/PLC_module_status.bob

 <?xml version="1.0" encoding="UTF-8"?>
 <display version="2.0.0">
+  <macros>
+    <SYMBOLS>../../symbols</SYMBOLS>
+  </macros>
   <name>Diag</name>
   <width>30</width>
   <height>70</height>
@@ -7,7 +10,7 @@
     <name>Disconnected</name>
     <pv_name>$(DIAG_CONN_STAT)</pv_name>
     <symbols>
-      <symbol>$(ESS_SYMBOLS=/ess-symbols)/badges/alarms/unconnected.svg</symbol>
+      <symbol>$(SYMBOLS)/alarms/unconnected.svg</symbol>
     </symbols>
     <x>3</x>
     <y>3</y>
@@ -24,7 +27,7 @@
     <name>Error</name>
     <pv_name>$(DIAG_STAT)</pv_name>
     <symbols>
-      <symbol>$(ESS_SYMBOLS=/ess-symbols)/badges/alarms/error.svg</symbol>
+      <symbol>$(SYMBOLS)/alarms/error.svg</symbol>
     </symbols>
     <x>3</x>
     <y>43</y>