Update host-containers to 0.21.0 and bootstrap-container to 0.3.0

[KCSesh]

Description of changes:

Bootstrap Container: v0.3.0
Admin Container: v0.21.0
Control Container: v0.21.0

Testing done:

bash-5.2# apiclient get settings.host-containers
{
  "settings": {
    "host-containers": {
      "admin": {
        "enabled": true,
        "source": "328549459982.dkr.ecr.us-west-2.amazonaws.com/bottlerocket-admin:v0.21.0",
        "superpowered": true,
        "user-data": "eyJzc2giOnsiYXV0aG9yaXplZC1rZXlzIjpbXX19"
      },
      "control": {
        "enabled": true,
        "source": "328549459982.dkr.ecr.us-west-2.amazonaws.com/bottlerocket-control:v0.21.0",
        "superpowered": false
      }
    }
  }
}

May 14 02:16:45 ip-172-31-49-195.us-west-2.compute.internal bootstrap-containers@test[2300]: 02:16:45 [INFO] Mode for 'test' is 'once'
May 14 02:16:45 ip-172-31-49-195.us-west-2.compute.internal bootstrap-containers@test[2300]: 02:16:45 [INFO] Turning off container 'test'
May 14 02:16:45 ip-172-31-49-195.us-west-2.compute.internal systemd[1]: Finished bootstrap container test.
bash-5.2# 
bash-5.2# 
bash-5.2# 
bash-5.2# apiclient get settings.bootstrap-containers
{
  "settings": {
    "bootstrap-containers": {
      "test": {
        "mode": "off",
        "source": "328549459982.dkr.ecr.us-west-2.amazonaws.com/bottlerocket-bootstrap:v0.3.0",
        "user-data": "IyEvYmluL2Jhc2gKZWNobyAnaGVsbG8gd29ybGQnCg=="
      }
    }
  }
}

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.