runtests.pl: fix precedence issue

The condition `!$cmdtype eq "perl"` (introduced in a4765b0551) is always
false. It checks whether a logical negation (giving true/false) is equal
to the string `"perl"`. This is impossible, so the logging never worked.

The intent was probably to negate the result of the string
comparison:`!($cmdtype eq "perl")` or simply `$cmdtype ne "perl"`.

Fixes #16128
Reported-by: Igor Todorovski
Closes #16129

tests/runtests.pl

@@ -1672,7 +1672,7 @@ sub singletest_check {
             my %cmdhash = getpartattr("client", "command");
             my $cmdtype = $cmdhash{'type'} || "default";
             logmsg "\n** ALERT! memory tracking with no output file?\n"
-                if(!$cmdtype eq "perl");
+                if($cmdtype ne "perl");
             $ok .= "-"; # problem with memory checking
         }
         else {