memdebug: stop tracking send and recv

- they rarely catch any problems
- we have other ways to test different send/recv problems
- the number of such calls vary much more per invoke than others, making
  memdebugging harder
- reducing the total number of fallible functions per test is good
- they were not used as intended anyway

Closes #20097

scripts/checksrc.pl

@@ -100,9 +100,7 @@ my %banfunc = (
     "open" => 1,
     "printf" => 1,
     "realloc" => 1,
-    "recv" => 1,
     "rename" => 1,
-    "send" => 1,
     "snprintf" => 1,
     "socket" => 1,
     "socketpair" => 1,