[stable-2.14] Exclude internal options from man pages and docs (#81360) (#81362)

(cherry picked from commit fead654671)

changelogs/fragments/suppressed-options.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - Exclude internal options from man pages and docs.

packaging/pep517_backend/_generate_man.py

@@ -50,6 +50,8 @@ def get_options(optlist):
 
     opts = []
     for opt in optlist:
+        if opt.help == argparse.SUPPRESS:
+            continue
         res = {
             'desc': opt.help,
             'options': opt.option_strings