Stop enabling the package_api_docs lint

The lint is non-functional and will be deprecated soon.

Bug: https://github.com/dart-lang/linter/issues/5107
Change-Id: I4d4b75a6c7978f584bef37351514391f55761c55
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389594
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Auto-Submit: Parker Lougheed <parlough@gmail.com>

benchmarks/analysis_options.yaml

@@ -49,7 +49,6 @@ linter:
     #- omit_local_variable_types
     #- only_throw_errors
     - overridden_fields
-    - package_api_docs
     - package_names
     - package_prefixed_library_names
     - prefer_adjacent_string_concatenation