tool_operate: remove call to abort()

Make an assert and return a plain error instead. No abort in release
code.

- also remove from two examples
- add as a banned function in checksrc
- document the banned state

Closes #22182

scripts/checksrc.pl

@@ -65,6 +65,7 @@ my %banfunc = (
     "_wfopen" => 1,
     "_wfreopen" => 1,
     "_wopen" => 1,
+    "abort" => 1,
     "accept" => 1,
     "accept4" => 1,
     "access" => 1,