fix: address invalid count bug

[RoseSecurity]

what and why

• If a data.aws_ssm_parameter.password.value is passed to this module, it is tagged as a sensitive in the AWS provider, and that tag travels with the value all the way into the module. Because we don’t mark variable master_password as sensitive = true, the value is off-limits to functions like length() or to meta-arguments like count. Terraform refuses to evaluate them → “invalid count argument”.

[RoseSecurity]

/terratest

[github-actions[bot]]

These changes were released in v0.27.0.