badwords: fix issues found in tests

There remain some false positives, hits in test data, and `dir` use,
around 100 issues in total.

There is no plan to enforce badwords on tests.

Also:
- badwords.txt: let a few `manpage[s]` occurrences through
  (in Perl code).

Closes #19541

tests/allversions.pm

@@ -33,7 +33,7 @@ our %pastversion;
 sub allversions {
     my ($file) = @_;
     open(A, "<$file") ||
-        die "can't open the versions file $file\n";
+        die "cannot open the versions file $file\n";
     my $before = 1;
     my $relcount;
     while(<A>) {