Remove leftover checker priority (#9429)

The concept of checker priority was removed[1] in Pylint 2.14.0[2].

[1]: e01fa86
[2]: https://pylint.readthedocs.io/en/v3.0.3/whatsnew/2/2.14/full.html#what-s-new-in-pylint-2-14-0

Author: naglis

pylint/checkers/dunder_methods.py

@@ -34,7 +34,6 @@ class DunderCallChecker(BaseChecker):
     """
 
     name = "unnecessary-dunder-call"
-    priority = -1
     msgs = {
         "C2801": (
             "Unnecessarily calls dunder method %s. %s.",

pylint/extensions/dunder.py

@@ -20,7 +20,6 @@ class DunderChecker(BaseChecker):
     """Checks related to dunder methods."""
 
     name = "dunder"
-    priority = -1
     msgs = {
         "W3201": (
             "Bad or misspelled dunder method name %s.",