Remove the two "VMS adjustments" from test.pl's _fresh_perl

Remove the two "VMS adjustments" from test.pl's _fresh_perl

These were added by commit ed6b3797850720f7 ("make t/op/misc.t work on VMS")
in Jan 2001 back when the relevant code was in t/op/misc.t

The two adjustments each only applied to one test in t/run/fresh_perl.t

Was:    system './perl -ne "print if eof" /dev/null'
Became: system './perl -ne "print if eof" NL:'

Was:    print "ok\n" if (-e _ and -f _ and -r _);
Became: print "ok\n" if (-e _ and -f _);

The latter had the comment "VMS file locking".

It seems that neither is needed now. Perl will recognise "/dev/null" as
the null device, and -r returns true on a file opened for reading.

The "adjustments", particularly the second, should have been done all along
in the code for the test itself, not by complicating the test runner.