[IMPROVE] Detector integration_azure-key-vault -> remove critical for API Latency

[freezeeedos]

What is the module?
integration_azure-key-vault

What is the detector?
api_latency

Is your improvement related to a known monitoring limitations? Please describe.
The API_LATENCY detector should not raise alerts of type "critical". These alerts are rarely acted upon, and a "major" severity is sufficent

Describe the solution you'd like
Shifting the severities for this detector from MAJOR and CRITICAL to MINOR and MAJOR

In terraform-signalfx-detectors/modules/integration_azure-key-vault/variables.tf:
api_latency_threshold_critical -> api_latency_threshold_major
api_latency_threshold_major -> api_latency_threshold_minor
Remove api_latency_disabled_critical

In terraform-signalfx-detectors/modules/integration_azure-key-vault/detectors-keyvault.tf:

    severity              = "Critical"
    detect_label          = "CRIT"
    disabled              = coalesce(var.api_latency_disabled_critical, var.api_latency_disabled, var.detectors_disabled)
    notifications         = try(coalescelist(lookup(var.api_latency_notifications, "critical", []), var.notifications.critical), null)

To

    description           = "is too high > ${var.api_latency_threshold_major}ms"
    severity              = "Major"
    detect_label          = "MAJOR"
    disabled              = coalesce(var.api_latency_disabled_major, var.api_latency_disabled, var.detectors_disabled)
    notifications         = try(coalescelist(lookup(var.api_latency_notifications, "major", []), var.notifications.major), null)

And

    description           = "is too high > ${var.api_latency_threshold_major}ms"
    severity              = "Major"
    detect_label          = "MAJOR"
    disabled              = coalesce(var.api_latency_disabled_major, var.api_latency_disabled, var.detectors_disabled)
    notifications         = try(coalescelist(lookup(var.api_latency_notifications, "major", []), var.notifications.major), null)

Would become

    description           = "is too high > ${var.api_latency_threshold_major}ms"
    severity              = "Minor"
    detect_label          = "MINOR"
    disabled              = coalesce(var.api_latency_disabled_major, var.api_latency_disabled, var.detectors_disabled)
    notifications         = try(coalescelist(lookup(var.api_latency_notifications, "major", []), var.notifications.major), null)

Describe alternatives you've considered
Overriding the parameters on each individual stack, which is not practical