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/pathhelp.pm

@@ -36,7 +36,7 @@
 # Forward slashes are simpler processed in Perl, do not require extra escaping
 # for shell (unlike back slashes) and accepted by Windows native programs, so
 # all functions return paths with only forward slashes.
-# All returned paths don't contain any duplicated slashes, only single slashes
+# All returned paths do not contain any duplicated slashes, only single slashes
 # are used as directory separators on output.
 # On non-Windows platforms functions acts as transparent wrappers for similar
 # Perl's functions or return unmodified string (depending on functionality),
@@ -195,7 +195,7 @@ sub dirsepadd {
 
 #######################################################################
 # Quote an argument for passing safely to a Bourne shell
-# This does the same thing as String::ShellQuote but doesn't need a package.
+# This does the same thing as String::ShellQuote but does not need a package.
 #
 sub shell_quote {
     my ($s)=@_;