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/data/test20

@@ -17,7 +17,7 @@ non-existing host
 http
 </features>
 <name>
-attempt connect to non-existing host name
+attempt connect to non-existing hostname
 </name>
 <command>
 --ipv4 non-existing-host.haxx.se.