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.

src/udev/generate-keyboard-keys-gperf.sh

@@ -17,4 +17,4 @@ _Pragma(\"GCC diagnostic ignored \\\"-Wimplicit-fallthrough\\\"\")\n\
 
     /^KEY_/ { print tolower(substr($1 ,5)) ", " $1 }
     { print tolower($1) ", " $1 }
-' < "${1:?}"
+' <"${1:?}"