tests: Directly diff expected_region_highlight against region_highlight

highlighters/main/test-data/sudo-command.zsh

@@ -43,7 +43,12 @@ expected_region_highlight=(
   "23 24 single-hyphen-option" # -i
   "26 27 command" # ls
   "29 29 path" # /
+  "30 30 commandseparator" # ;
+  "32 35 precommand" # sudo
   "37 37 unknown-token" # ;, error because empty command
+  "39 42 precommand" # sudo
+  "44 45 single-hyphen-option" # -u
   "47 47 unknown-token" # ;, error because incomplete command
+  "49 52 precommand" # sudo
   "54 64 unknown-token" # notacommand - doesn't falls back to "not a command word" codepath
 )