AWS::EC2::Instance - BlockDeviceMapping-Ebs-When modifying from GP2 to GP3 Should use equivalent GP3 IOPS and Throughput

### Name of the resource

AWS::EC2::Instance

### Resource name

_No response_

### Description

# 1. Title
AWS::EC2::Instance - BlockDeviceMapping-Ebs-When modifying from GP2 to GP3 Should use equivalent GP3 IOPS and Throughput

# 2. Expected Behaviour
When GP2 volume types are modified to GP3 in the the Ebs Resource inside `AWS::EC2::Instance` the throughput value of the GP3 volume must be the GP2 equivalent throughput value.

# 3. Expected Behaviour
Today the throughput defaults to the value of 125.

# 4. Additional details
When GP2 instances are modified to GP3, the `AWS::EC2::Volume` resource automatically calculates the GP3 equivalent throughput value as documented in this [excel sheet](https://d1.awsstatic.com/product-marketing/Storage/EBS/gp2_gp3_CostOptimizer.dd5eac2187ef7678f4922fcc3d96982992964ba5.xlsx) on the [EBS Resources page](https://aws.amazon.com/ebs/resources/). This request is to make sure that AWS::EC2::Instance-BlockDeviceMapping-Ebs also does the same.

This also goes against the spirit (not the letter of it, because CFN is not mentioned in the link) of what we have said in the documentation here: https://aws.amazon.com/about-aws/whats-new/2022/07/amazon-ebs-elastic-volumes-automated-settings-modify-volumes-costs/

# 5. Related issues
- #824 - This issue already prevents us from specifying a Throughput value. Thus, at the moment, there is no way to override the default throughput value of 125.

### Other Details

_No response_

Start by reviewing AWS::EC2::Instance BlockDeviceMapping-Ebs behavior for GP2-to-GP3 modifications and compare it with the AWS::EC2::Volume behavior described in the issue. Check related issue #824 and the linked AWS EBS resources; done means the instance path preserves the equivalent GP3 IOPS and throughput instead of defaulting throughput to 125.

Written by the indexing model from the issue text.