lint: Disable react/static-property-placement before buggy upgrade

Starting in version 7.31.9 of eslint-plugin-react, this rule has
a bug where it talks about `contextTypes` when in reality we don't
have and never want a `contextTypes`:
  jsx-eslint/eslint-plugin-react#3467

Just disable the rule -- it's not a valuable enough rule to spend
effort hacking around the bug.

.eslintrc.yaml

@@ -128,10 +128,11 @@ rules:
   # better aligns with our practices in JS proper (not JSX).
   react/jsx-curly-newline: off
 
-  # Enforce `static` class property syntax.
-  react/static-property-placement:
-    - error
-    - static public field
+  # This rule has a bug that causes annoying irrelevant messages:
+  #   https://github.com/jsx-eslint/eslint-plugin-react/issues/3467
+  # The rule isn't important enough to be worth hacking around,
+  # especially now that we have few remaining class components.
+  react/static-property-placement: off
 
   # Enforce state initialization style (never in constructor)
   react/state-in-constructor: