fix: unquote references in ignore_changes

[svrakitin]

what

• remove terraform 0.11 warnings, i.e.:

  
  on .terraform/modules/emr_cluster/main.tf line 467, in resource "aws_emr_cluster" "default":
  467:     ignore_changes = ["kerberos_attributes", "step", "configurations_json"]

In this context, references are expected literally rather than in quotes. Terraform 0.11 and earlier required quotes, but quoted references are now deprecated and will be removed in a future version of Terraform. Remove the quotes surrounding this reference to silence this warning.

## why
* avoid these warnings in logs

[nitrocode]

/test all

[aknysh]

/rebuild-readme

[aknysh]

/terraform-fmt

[aknysh]

/test all