MDEV-23697: bin/env perl -i -> bin/perl -i

- reverting 37c88445 doesn't mean adding space where shouldn't been
- /bin/perl instead of /bin perl

scripts/convert-debug-for-diff.sh

-#!/usr/bin perl -i
+#!/usr/bin/perl -i
 #
 # This script converts all numbers that look like addresses or memory sizes,
 # in a debug files generated by --debug (like mysqld --debug-dbug), to #.