IamInstanceProfile option ignored in create / deploy

### Description

When using .ebextensions custom configs I provide a value for the property IamInstanceProfile under the aws:autoscaling:launchconfiguration namespace. When calling `eb create` or `eb deploy` this value is ignored and instead uses the default `aws-elasticbeanstalk-ec2-role` role. If I edit the config via `eb config` and set the IamInstanceProfile property to null, it correctly sets the role according to what is in .ebextensions suggesting the config files themselves are fine.

### Steps to reproduce

Any standard setup, with the addition of an .ebextensions config file including the content:

```
option_settings:
aws:autoscaling:launchconfiguration:
IamInstanceProfile: name-of-an-existing-profile
```

Run `eb create` with usual params, making sure no `-ip` flag is provided.

### Expected result

Would expect the environment to be created or updated with the value existing in the relevant namespace option.

### Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: Amazon Linux 2
2. EBCLI version: 3.20.2

Start by reproducing the issue with the shown .ebextensions option_settings entry, then compare the option handling in eb create, eb deploy, and eb config when no -ip flag is supplied. Done means the existing IamInstanceProfile value is honored during create and deploy, with regression coverage added if the relevant test entry point is found.

Written by the indexing model from the issue text.