Remove a keystore key is not possible

[kuisathaverat]

Readiness Checklist

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed
• I am reporting the issue to the correct repository (for multi-repository projects)

Expected Behavior

When you remove a key from the keystone configuration, it should be removed from the deployment.

Current Behavior

The key is not removed

## Terraform definition

Create configuration A

terraform {
  required_version = ">= 0.12.29"

  required_providers {
    ec = {
      source  = "elastic/ec"
      version = "0.12.2"
    }
  }
}

provider "ec" {
  endpoint = "https://my.ece-environment.corp"
  insecure = true
  apikey = "my-apikey"
}

data "ec_stack" "latest" {
  version_regex = "latest"
  region        = "us-east-1"
}

resource "ec_deployment" "example_minimal" {
  name = "my_example_deployment"
  region                 = "us-east-1"
  version                = data.ec_stack.latest.version
  deployment_template_id = "aws-io-optimized-v2"
  elasticsearch = {
    hot = {
      autoscaling = {}
    }
    keystore_contents = {
    "gcs.client.external.credentials_file" = {
      value         = file("./gcp-credentials.json")
      as_file       = true
    }
  }
}

Update configuration B without the key

terraform {
  required_version = ">= 0.12.29"

  required_providers {
    ec = {
      source  = "elastic/ec"
      version = "0.12.2"
    }
  }
}

provider "ec" {
  endpoint = "https://my.ece-environment.corp"
  insecure = true
  apikey = "my-apikey"
}

data "ec_stack" "latest" {
  version_regex = "latest"
  region        = "us-east-1"
}

resource "ec_deployment" "example_minimal" {
  name = "my_example_deployment"
  region                 = "us-east-1"
  version                = data.ec_stack.latest.version
  deployment_template_id = "aws-io-optimized-v2"
  elasticsearch = {
    hot = {
      autoscaling = {}
    }
}

Steps to Reproduce

1. create a deployment with the configuration A (see below)
2. update the deployment with the configuration B
3. Check that the keystore still contains the key gcs.client.external.credentials_file

Context

Possible Solution

The workaround is remove the key manually from the UI.

Your Environment

• Version used: 0.12.2
• Running against Elastic Cloud SaaS or Elastic Cloud Enterprise and version: ECH production
• Environment name and version (e.g. Go 1.9):
• Server type and version:
• Operating System and version:
• Link to your project: