fix: removing the deprecated enabled value for diagnostic settings metrics

[MacMur85]

Description

A change to the implementation of the Diagnostic Setting module required to eliminate the deprecated form of metric definition.

Old implementation:

module "diagnostic-settings" {
  source = "../diagnostic-settings"

  name                       = "${var.name}-diagnostic-setting"
  target_resource_id         = azurerm_api_management.apim.id
  log_analytics_workspace_id = var.log_analytics_workspace_id
  enabled_log                = var.monitor_diagnostic_setting_apim_enabled_logs
  metric                     = var.monitor_diagnostic_setting_apim_metrics
  metric_enabled             = var.metric_enabled
}

New implementation:

module "diagnostic-settings" {

  source = "../diagnostic-settings"

  name                       = "${var.name}-diagnostic-setting"
  target_resource_id         = azurerm_api_management.apim.id
  log_analytics_workspace_id = var.log_analytics_workspace_id
  enabled_log                = var.monitor_diagnostic_setting_apim_enabled_logs
  enabled_metric             = var.monitor_diagnostic_setting_apim_metrics
}

Context

This change requires making modifications to all the repositories using this module!
An example of needed changes can be found in the Cohort-Manager repo: PR-1543

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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