Correct exit using, the exit status should be 0~255

According to the POSIX Programmer's Manual, the exit status specified by
the unsigned decimal integer. If n is specified, but its value is not
between 0 and 255 inclusively, the exit status is undefined.

By cross reference the usage between different scripts in this project,
it looks like we could simply remove the `-` before the number.

utils/00_unittest_baseline.sh

@@ -28,7 +28,7 @@ check_result() {
 
      remove_quotes
      json_result="$(awk '/id.*'"${1}"'/,/finding.*$/' $FILE)"
-     [[ -z $json_result ]] && exit -1
+     [[ -z $json_result ]] && exit 1
      # is4lines?
      finding_value="$(awk -F':' '/finding/ { print $2" "$3" "$4 }' <<< "$json_result")"
      if [[ $# -eq 2 ]]; then