Add refactoring for datadog scaler

[dttung2905]

Refactoring the datadog scaler. It a little bit more complicated than I have imagined. There are a few TODO that I will resolve before marking this PR ready

Checklist

• I have verified that my change is according to the deprecations & breaking changes policy
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Relates to #5797

[dttung2905]

@kedacore/keda-maintainers Hi team, I have one question and would need your help 🙏 . Are we ready to deprecate vType ? it has been flagged out in the PR #3491 2 years ago

keda/pkg/scalers/datadog_scaler.go

Lines 254 to 265 in 30ddff3

	if val, ok := config.TriggerMetadata["type"]; ok {
	logger.V(0).Info("trigger.metadata.type is deprecated in favor of trigger.metricType")
	if config.MetricType != "" {
	return nil, fmt.Errorf("only one of trigger.metadata.type or trigger.metricType should be defined")
	}
	val = strings.ToLower(val)
	switch val {
	case avgString:
	meta.vType = v2.AverageValueMetricType
	case "global":
	meta.vType = v2.ValueMetricType
	default:

I'm slightly confused as it is also metntioned as part of the test case in

keda/pkg/scalers/datadog_scaler_test.go

Line 111 in 30ddff3

{v2.AverageValueMetricType, map[string]string{"useClusterAgentProxy": "true", "datadogMetricName": "nginx-hits", "datadogMetricNamespace": "default", "targetValue": "2", "type": "global"}, map[string]string{"token": "token", "datadogNamespace": "datadog", "datadogMetricsService": "datadog-cluster-agent-metrics-api", "unsafeSsl": "true", "authMode": "bearer"}, true},

[wozniakjan]

for best expert opinion, I would like to ping @arapulido

[dttung2905]

Thanks @wozniakjan ,for now I will just focus on the refactoring and leave this for another time

[dttung2905]

/run-e2e datadog
Update: You can check the progress here

[wozniakjan]

the refactor looks pretty good but probably some small regression has been added because it seems that e2e tests are failing now

    helper.go:4***7: Waiting for deployment replicas to hit target. Deployment - datadog-dca-test-deployment, Current  - ***, Target - 0
    datadog_dca_test.go:***58: 
        	Error Trace:	/__w/keda/keda/tests/sequential/datadog_dca/datadog_dca_test.go:***58
        	Error:      	Should be true
        	Test:       	TestDatadogScalerDCA
        	Messages:   	replica count should be 0 after *** minutes
    datadog_dca_test.go:***68: --- testing activation ---
    helper.go:54***: Applying template: lightLoadTemplate
    helper.go:494: Waiting for some time to ensure deployment replica count doesn't change from 0
    helper.go:50***: Deployment - datadog-dca-test-deployment, Current  - ***
    helper.go:504: 
        	Error Trace:	/__w/keda/keda/tests/helper/helper.go:504
        	            				/__w/keda/keda/tests/sequential/datadog_dca/datadog_dca_test.go:***7***
        	            				/__w/keda/keda/tests/sequential/datadog_dca/datadog_dca_test.go:***6***
        	Error:      	datadog-dca-test-deployment replica count has changed from 0 to ***
        	Test:       	TestDatadogScalerDCA
    datadog_dca_test.go:***75: --- testing scale out ---
...

Failed tests:
	Execution of tests/sequential/datadog_dca/datadog_dca_test.go, has failed after "two" attempts
make: *** [Makefile:***09: e***e-test] Error ***

[dttung2905]

/run-e2e datadog
Update: You can check the progress here