Allow no interruption to TGW attachment when updating

### Name of the resource

AWS::EC2::TransitGatewayAttachment

### Resource name

_No response_

### Description

Updates to EC2::TGWAttachment currently replaces the TGW resource. I would like the ability to update Tags to TGW attachments without interruption to the resources, as this current operation will replace the resource and impact TGW routing.

### Other Details

_No response_

Start by reviewing the AWS::EC2::TransitGatewayAttachment resource behavior described in the issue, especially how tag updates are classified. No repository files, tests, or implementation entry points are named in the payload. Done means tag updates no longer replace the attachment or interrupt TGW routing, with coverage demonstrating that behavior.

Written by the indexing model from the issue text.