Export max_retries as an environment variable

[linouk23]

What

provider "confluent" {
  cloud_api_key    = var.confluent_cloud_api_key
  cloud_api_secret = var.confluent_cloud_api_secret
  max_retries = 10
}

The ask is to be able to supply a value for max_retries via an environment variable.

[linouk23]

This was added in 1.50.0: https://github.com/confluentinc/terraform-provider-confluent/blob/master/CHANGELOG.md#1500-july-21-2023.

In short, one can use TF_PROVIDER_CONFLUENT_MAX_RETRIES env variable to set max_retries variable.