Use CLOUD_IAM_SERVICE_ACCOUNT for MySQL variation

[NimJay]

Background:

• There are two variations of this Three-tier web app:
  • PostgreSQL
  • MySQL
• The CLOUD_IAM_SERVICE_ACCOUNT for each variation looks different:

resource "google_sql_user" "main" {
...
  name            = var.database_type == "postgresql" ? "${google_service_account.runsa.account_id}@${var.project_id}.iam" : "foo"
  type            = var.database_type == "postgresql" ? "CLOUD_IAM_SERVICE_ACCOUNT" : null
  password        = var.database_type == "mysql" ? "bar" : null

• This discussion thread states that type = "CLOUD_IAM_SERVICE_ACCOUNT" didn't work for MySQL right out of the box.
• This CLOUD_IAM_SERVICE_ACCOUNT option allows us to use Cloud Run's service account to access the database in CloudSQL.

Feature request:

• Use CLOUD_IAM_SERVICE_ACCOUNT for the MySQL variation too. According to the docs, CLOUD_IAM_SERVICE_ACCOUNT is supported for both PostgreSQL an MySQL.