feat: set evidence-based memory requests for backend and mgmt-agent

[weherdh]

https://redhat.atlassian.net/browse/AROSLSRE-1033
https://redhat.atlassian.net/browse/AROSLSRE-1654

What

Set evidence-based memory requests for two services that are currently under-provisioned:

• backend: 500Mi → 1Gi (was running at 1.5–3.25x its request in uksouth)
• mgmt-agent: 64Mi → 768Mi (was running at 8–10x its request — 64Mi was never a real sizing)

Also wires mgmt-agent's resource values through config.yaml instead of hardcoded defaults in values.yaml.

Why

Both services have memory requests that don't reflect actual production usage:

• backend in uksouth consistently uses 750MB–1GB, but its request was 500Mi. This caused 49 alert firings/week with the new generic ServiceMemoryDrift alert (PR feat: add generic memory drift and trend alerts for ARO-HCP services #6011).
• mgmt-agent uses 256–512MB steady-state (peak <768MB), but its request was 64Mi — providing no meaningful scheduling signal or eviction protection.

Evidence gathered by running alert-tester against prod Grafana (container_memory_working_set_bytes) across uksouth, eastus2, and australiaeast for July 21–28.

Testing

• make materialize passes — rendered configs and helm fixtures regenerated
• No code changes; config-only PR
• The generic ServiceMemoryDrift alert (PR feat: add generic memory drift and trend alerts for ARO-HCP services #6011) will validate these values once deployed — right-sized requests should produce 0 firings

Special notes for your reviewer

• The mgmt-agent values.yaml now references {{ .mgmtAgent.k8s.resources.requests.memory }} instead of a hardcoded 64Mi, consistent with how other services (backend, kube-applier) wire their resource values.
• Priority class changes are tracked separately and will follow.

PR Checklist

• PR is scoped to a single task (no mixed concerns)
• Title follows Conventional Commits format
• Summary explains the "Why" behind the change
• Linked to relevant ticket/issue
• Screenshots included (if graph/UI/metrics changes)
• Self-reviewed the diff
• CI/CD checks are passing (ignore Tide)
• Draft PR used for WIP (if applicable)
• Commit history is clean (rebased/squashed)
• Tricky code blocks are commented
• Specific reviewers tagged
• All comment threads resolved before merge

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[Copilot]

Pull request overview

Adjusts Kubernetes memory requests for the backend and mgmt-agent services to better reflect observed production usage, and standardizes mgmt-agent resource configuration by sourcing requests from config.yaml rather than hardcoded chart defaults.

Changes:

• Increase backend memory request default from 500Mi to 1Gi.
• Increase mgmt-agent memory request from 64Mi to 768Mi.
• Wire mgmt-agent request values through config.yaml and regenerate rendered configs / Helm fixtures.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
mgmt-agent/zz_fixture_TestHelmTemplate_dev_westus3_mgmt_1_mgmt_agent.yaml	Updates Helm fixture to reflect new mgmt-agent memory request (768Mi).
mgmt-agent/values.yaml	Sources mgmt-agent resource requests from config.yaml instead of hardcoded values.
config/rendered/dev/pers/westus3.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/rendered/dev/perf/westus3.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/rendered/dev/dev/westus3.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/rendered/dev/cspr/westus3.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/rendered/dev/ci01/centralus.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/rendered/dev/ci00/centralus.yaml	Rendered config updated for backend (1Gi) and mgmt-agent resources.
config/config.yaml	Updates defaults: backend request to 1Gi; adds mgmt-agent resources defaults.
backend/zz_fixture_TestHelmTemplate_dev_westus3_svc_1_aro_hcp_backend_dev.yaml	Updates backend Helm fixture to reflect new memory request (1Gi).
backend/testdata/zz_fixture_TestHelmTemplate_backend_mi_mock_and_arm_perms_mgr_identities_unset.yaml	Updates backend test fixture to reflect new memory request (1Gi).
backend/testdata/zz_fixture_TestHelmTemplate_backend_clstr_scoped_identities_role_set_name_public.yaml	Updates backend test fixture to reflect new memory request (1Gi).

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.