Remove backwards compatibility support for deprecated inline IAM policies in S3 shares

[dlpzx]

Is your idea related to a problem? Please describe.
In 2.3 IAM permissions needed for accessing S3 resources granted in s3-bucket-sharing and s3-access-points sharing were modified. Instead of using inline IAM policies, it introduced managed IAM policies (see PR: #1068). Currently if a share is using the old inline policy, data.all updates it to use managed policies if any sharing action happens on the share request (e.g. new items added to the share request).

There have been a number of releases between 2.3 and the next one 2.7 for users to get familiar with the new way of handling requestor permissions in data.all and to upgrade their current shares.

Describe the solution you'd like
I would like data.all codebase to be manageable and without dead code. For this reason I submit this request to remove the backwards compatibility code that supports inline IAM to Managed IAM policy migration.

P.S. Don't attach files. Please, prefer add code snippets directly in the message body.