Creds in snow does not allow space

## Actual behaviour
When the line of snow creds file containing whitespace at the end:
```
[10.0.0.1]
aws_access_key_id = ***
aws_secret_access_key = ***
region = snow
```

`create cluster -f ./cluster.yaml -v 99` would fail:
```
Error: getting device ips from aws credentials: no ip address profile found in content
```

## Expected behaviour
No error getting device ips from aws credentials

Start by searching the exact error text, "no ip address profile found in content," and trace the credential parsing used by `create cluster -f ./cluster.yaml -v 99`. Reproduce the trailing-space case from the issue, add coverage for it, and verify that the command no longer fails while reading AWS credentials.

Written by the indexing model from the issue text.