Terraform squad-owned monitors in Datadog

[timmc-edx]

A/C:

• Created Terraform module for squad-based ownership monitors (apdex, error rate)
• Migrated relevant Arch-BOM monitors to use module
• Updated https://2u-internal.atlassian.net/wiki/spaces/ENG/pages/1083605119/Squad-owned+LMS+Datadog+alert+runbook#Creating-monitors with pointer to new Terraform config
• Informed teams and suggested that they migrate their monitors as well

Notes:

• Existing PR: https://github.com/edx/terraform/pull/7000

[timmc-edx]

I got most of the work done in a couple of branches but ran into some Terraform difficulties, and it just wasn't high enough priority, so dropping it for now:

• Module, in a personal repo while I was experimenting: timmc-edx/tf-module-datadog-apm-lms-by-squad@main...timmc/apdex
• PR to create monitors for Arch-BOM using that module: https://github.com/edx/terraform/pull/7000
• Slack thread: https://twou.slack.com/archives/C02N1RGCH/p1717444551912229