Inria CI "main" script: do not lower priority on macOS

I suspect "renice 10" has bad consequences on the Mac M1, so let's see
if removing it makes a difference.

tools/ci/inria/main

@@ -93,7 +93,7 @@ esac
 
 # be considerate towards other potential users of the test machine
 case "${OCAML_ARCH}" in
-  bsd|macos|linux) renice 10 $$ ;;
+  bsd|linux) renice 10 $$ ;;
 esac
 
 # be verbose and stop on error