Chore: adding Datadog monitoring middleware

[pmakwana93]

Description:
Adding Datadog monitoring middleware as per https://docs.google.com/spreadsheets/d/1sh9eE-vT5JysI4BAx_qlkhzZ0hEujM_B18qL4XQoq1k/edit?gid=56476385#gid=56476385

Slack reference: https://twou.slack.com/archives/C0495EETUVC/p1724856564259579

JIRA: ENT-9422

Merge checklist:

• ./manage.py makemigrations has been run
  • Note: This must be run if you modified any models.
    • It may or may not make a migration depending on exactly what you modified, but it should still be run.

Post merge:

• Ensure that your changes went out to the stage instance
• Deploy to prod instance

[marlonkeating]

nit: Keeping comment next to relevant import

Suggested change

	# Enables monitoring utility for writing custom metrics.
	'edx_django_utils.monitoring.DeploymentMonitoringMiddleware',
	'edx_django_utils.monitoring.middleware.MonitoringCustomMetricsMiddleware',
	'edx_django_utils.monitoring.DeploymentMonitoringMiddleware',
	# Enables monitoring utility for writing custom metrics.
	'edx_django_utils.monitoring.middleware.MonitoringCustomMetricsMiddleware',