docs: drop AWS account scanning

[knqyf263]

Description

Trivy no longer includes live cloud scanning as part of the core Trivy experience. This PR deletes AWS scanning from the documentation.

Related issues

• DEPRECATION: Sunset `trivy aws` subcommand from Trivy v0.53+ #6818

Related PRs

• https://github.com/aquasecurity/trivy/pull/6995v

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[nikpivkin]

A couple other places where the trivy-aws command is mentioned
https://github.com/aquasecurity/trivy/blob/main/docs/tutorials/shell/shell-completion.md?plain=1#L52
https://github.com/aquasecurity/trivy/blob/main/docs/docs/configuration/reporting.md?plain=1#L431

[knqyf263]

Thanks. Fixed.

[knqyf263]

@simar7 It's a trivial change, so I'll merge it. If you have any feedback, we can open a follow-up PR later before we deploy this change.