test: drop whitespace after shell redirection operators

(The one case that is left unchanged is '< <(subcommand)'.)

This way, the style with no gap was already dominant. This way, the reader
immediately knows that ' < ' is a comparison operator and ' << ' is a shift.

In a few cases, replace custom EOF replacement by just EOF. There is no point
in using someting like "_EOL" unless "EOF" appears in the text.

tools/debug-sd-boot.sh

@@ -60,7 +60,7 @@ while read -r line; do
         data="${BASH_REMATCH[2]}"
         break
     fi
-done < "${2}"
+done <"${2}"
 
 if [[ -z "${text}" || -z "${data}" ]]; then
     echo "Could not determine text and data location."