ci: Add FreeRTOS upstream files to the sonar exclude list

These files are mostly upstream code apart from some minor modifications.
There are a number of places that sonarqube reports issues because of
different code style/expectations.

tools/ci/sonar_exclude_list.txt

@@ -4,3 +4,7 @@
 # - test/*/*.c
 # - test.c
 # lines start with # will be ignored
+
+# FreeRTOS upstream code (don't include our port files here)
+- components/freertos/*.c
+- components/freertos/include/freertos/*.h