Add DD_AGENT_IPC_* env vars

[mackjmr]

What this PR does / why we need it:

This PR adds DD_AGENT_IPC_PORT and DD_AGENT_IPC_CONFIG_REFRESH_INTERVAL env vars in otel agent and core agent. It does not override them if they are added by the user. This is necessary for the otel-agent to pull the api key from core config in the case where backend secrets are used.

This PR also adds flag --sync-delay=30s to otel agent.

Which issue this PR fixes

OTEL-2323

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• Chart Version bumped
• Documentation has been updated with helm-docs (run: .github/helm-docs.sh)
• CHANGELOG.md has been updated
• Variables are documented in the README.md
• For Datadog Operator chart or value changes update the test baselines (run: make update-test-baselines)

[levan-m]

Could you please consider adding test like this to make sure chart doesn't break and it works as intended.

[levan-m]

Could you extract the $found computation to _helpers.tpl? like this e.g.:

helm-charts/charts/datadog/templates/_helpers.tpl

Lines 992 to 1001 in 788d28d

	{{/*
	Return value of "DD_PROCESS_CONFIG_RUN_IN_CORE_AGENT_ENABLED" env var in core agent container.
	*/}}
	{{- define "get-process-checks-in-core-agent-envvar" -}}
	{{- range .Values.agents.containers.agent.env -}}
	{{- if eq .name "DD_PROCESS_CONFIG_RUN_IN_CORE_AGENT_ENABLED" -}}
	{{- .value -}}
	{{- end -}}
	{{- end -}}
	{{- end -}}

[mackjmr]

Moved logic to helpers in: 267473a.

[levan-m]

I don't see this or DD_AGENT_IPC_PORT used elsewhere in the chart, do we expect them to be added?

[mackjmr]

Youre right, we dont set this in helm charts. This is to make sure we don't override it if the user sets it in datadog.env, Values.agents.containers.agent.env or Values.agents.containers.otelAgent.env.

[mackjmr]

Thanks for the review @levan-m, I've addressed the feedback and added a test in: a20b97c. Unfortunately, it seems like I am unable to test the option to not override user provided env vars, as setting something like:

					"datadog.env": `
- name: DD_AGENT_IPC_PORT
  value: 1234
- name: DD_AGENT_IPC_CONFIG_REFRESH_INTERVAL
  value: 13`,

in the test cases does not reflect these env vars in the test results, so I am guessing this gets done at another stage ? I've tested this manually in a test k8s cluster, and the not override logic is taken into account, I'm just not able to test this programatically.

I was getting the same issue in not being able to test that we don't override in the operator PR: DataDog/datadog-operator#1604 (comment).