Ssh command fails when ssh agent try many identity files

### Description

The`eb ssh` command attaches the identity file related to your EB instance, however ssh client not only offer the identity file specified with ssh param `-i` but also all other identity files that ssh agent has access on your machine. It causes a rejection with message "Too many authentication failures", when ssh agent presents to aws instance those identify files before the one ssh command specify with the param `-i`

### Steps to reproduce

This can be reproduced by issuing a ssh command to your EB instance with more than 6 identify files in your ~/.ssh folder

### Observed result
A rejection message : "Too many authentication failures" as below:

```
INFO: Running ssh -i file.pem ec2-user@--.--.--.--
Received disconnect from --.--.--.-- port 22:2: Too many authentication failures
Disconnected from --.--.--.-- port 22
```

### Expected result

A successful ssh terminal prompt into EB instance

### Additional environment details

1. OS: Linux
2. EBCLI version: 3.20.3

Start with the implementation of the `eb ssh` command and reproduce the failure using more than six identity files in `~/.ssh` on Linux. Trace how the command invokes SSH, then verify that the command reaches a successful terminal prompt without the “Too many authentication failures” message.

Written by the indexing model from the issue text.