qapi: Disable similarity checks in pylint entirely

The pylint similarity checks cannot distinguish parameter lists from
other code; with the QAPISchemaVisitor interface having long lists of
parameters, these similarity checks fire off in a way that's difficult
to disable in a targeted way without littering the code with pylint
pragmas.

There is a change request filed to be able to ignore parameter lists,
see: pylint-dev/pylint#3619

scripts/qapi/pylintrc

@@ -18,6 +18,7 @@ ignore-patterns=schema.py,
 # --disable=W".
 disable=fixme,
         missing-docstring,
+        similarities, # See https://github.com/PyCQA/pylint/issues/3619
         too-many-arguments,
         too-many-branches,
         too-many-statements,