RBS added to aws-sdk-ruby gem itself

[ksss]

https://aws.amazon.com/jp/blogs/developer/announcing-rbs-support-for-aws-sdk-for-ruby-v3/

All aws-sdk-ruby related gems now include RBS.
Therefore, the gem_rbs_collection side seems to be no longer needed.
How do we deal with this?

Possible problem

The RBS on the gem_rbs_collection side is not compatible with the RBS on the gem side.
Using aws-sdk-core on gem_rbs_collection side and aws-sdk-xray on gem side will cause problems when reading RBS.

Idea

• Leave the gem_rbs_collection side for a while.
• Remove gem_rbs_collection/aws-sdk-*.