Remove obsolete custom service package code

[normj]

Description

This PR goes through the service packages except for S3 and drops most all code that is marked as obsolete. The main code that is left that is obsolete is the DynamoDB HLL code that was just marked as obsolete as part of V4.

Overall changes:

CloudFront

• Removed the AmazonCloudFrontUtil utility class. It was only available for .NET Framework and the methods were mostly redirects to other Core pieces of code. PR Mark code that has been deleted in V4 as obsolete in V3 #3685 for V3 marks the type as obsolete.

DynamoDB:

• Removed the DynamoDBContextTableNamePrefix property. Users should call AWSConfigsDynamoDB.Context.TableNamePrefix instead of AWSConfigsDynamoDB.Context.DynamoDBContextTableNamePrefix.

EC2:

• Removed the VPC utilizes code. It was terribly out of date even referring to EC2 instance type that has been deprecated for years.
• Removed the image utilities used for looking up EC2 amis for Windows OS. The last update to this utility was for Windows Server 2016. We never updated for any newer OSs and there are better ways through SSM to get this information.
• This PR for V3 will mark this deleted code as obsolete in V3. Mark code that has been deleted in V4 as obsolete in V3 #3685

IoT

• Removed a legacy customization for NextToken override to refer to the actual modeled pagination token. My assumption is when this service was first launch there was a model issue that was corrected and we added this customization to avoid breaking changes. After this many years I have to assume people have switched to the real modeled field.

Lambda

• I added the customization for code generation to exclude the InvokeAsync deprecated method. I know we don't remove deprecated modeled operations but always felt this method having an Async suffix makes the Lambda client confusing with the supported Invoke method which we generate as InvokeAsync for the async use case. The original deprecated method's name doesn't work well for .NET. Since it is deprecated there is no reason to keep it.

SageMager

• Removed the customizations that were used to maintain backwards compatible in the event objects once we fixed the code generator to properly generate the event objects.

SecurityToken

• Removed the deprecated STS assume role credential provider since users should be using the one in core.

Testing

Dry Run: DRY_RUN-ef79ca15-4cb5-494a-80f4-2085ece52132 Successful

[normj]

I made this change to avoid the SDK generating a lot of JsonExceptions being thrown when an empty string is being sent in.

[dscpinheiro]

Nice! I think we even have a canary that checks this file can be downloaded, we can turn that off as well.

Waiting to see if V3 sync will be performed first.