Remove useless ignore rules

Those rules are not part of lints/recommended, but were not cleaned when
migrating from pedantic.

analysis/lib/analysis_options.yaml

@@ -11,16 +11,12 @@ analyzer:
     # These are necessary for matching the JS API.
     avoid_types_as_parameter_names: ignore
 
-    # This has tons of false positives for StreamSubscription.close().
-    unawaited_futures: ignore
-
     # These are style preferences rather than potential semantic issues. While
     # we're not intrinsically opposed to adopting them for consistency with the
     # Dart ecosystem, there aren't currently any automated tools to help us
     # migrate to and remain consistent with these style rules, so achieving
     # consistency isn't worth the engineering time we'd spend getting there.
     annotate_overrides: ignore
-    prefer_single_quotes: ignore
     use_function_type_syntax_for_parameters: ignore
 
 include: package:lints/recommended.yaml