feat: add global.images registry, pullSecrets, and pullPolicy support to nri-bundle charts

[dpacheconr]

Summary

Add support for cascading registry, pullSecrets, and pullPolicy from global settings across multiple nri-bundle charts.

Phase 1: Global.Images.Registry Support ✅

• newrelic-logging: Busybox init container (fluentBit.persistenceInitContainerImage) now respects global.images.registry
• Added helper newrelic-logging.persistenceInitContainerImage in _helpers.tpl
• Updated daemonset.yaml to use the helper

Phase 2: Global.Images.PullSecrets Support ✅

• newrelic-pixie: Added imagePullSecrets helpers and updated job.yaml
• nr-ebpf-agent: Updated both daemonsets (nr-ebpf-agent-daemonset.yaml, otel-collector-daemonset.yaml)
• newrelic-logging: Updated daemonset.yaml to include global.images.pullSecrets

Phase 3: Global.Images.PullPolicy Support ✅ (NEW)

• newrelic-logging: Added pullPolicy helpers in _helpers.tpl
• Updated daemonset.yaml to use pullPolicy helpers for main and init containers
• Configuration respects hierarchy: global setting → chart-level setting → default (IfNotPresent)

Changes by Chart

newrelic-logging (Phase 1 + Phase 2 + Phase 3)

Files Changed:

• charts/newrelic-logging/values.yaml - Added persistenceInitContainerImage configuration
• charts/newrelic-logging/templates/_helpers.tpl - Added registry and pullPolicy helpers
• charts/newrelic-logging/templates/daemonset.yaml - Updated init container and imagePullSecrets/pullPolicy rendering

Configuration Hierarchy:

• Registry: global.images.registry → fluentBit.persistenceInitContainerImage.repository
• PullSecrets: global.images.pullSecrets → image.pullSecrets
• PullPolicy: global.images.pullPolicy → fluentBit.image.pullPolicy

Test Plan

Phase 1 (newrelic-logging Registry):

• ✓ Global registry is used when set: my.private.registry.com/busybox:1.36
• ✓ Defaults to standard image when global registry not configured: busybox:1.36
• ✓ Explicit repository configuration overrides global registry

Phase 2 (PullSecrets):

• ✓ No pullSecrets set → No imagePullSecrets section rendered
• ✓ Global pullSecrets only → Uses global across all charts
• ✓ Both global + chart pullSecrets → Uses both (global items first)

Phase 3 (PullPolicy):

• ✓ Global pullPolicy is used when set and no chart-level policy exists
• ✓ Defaults to IfNotPresent when neither global nor chart policy is set
• ✓ Explicit chart-level pullPolicy overrides global setting

Impact

Once merged, users can now configure image pull behavior globally:

```yaml
global:
images:
registry: "my.private.registry.com"
pullSecrets:
- name: my-registry-credentials
pullPolicy: Always
```

This eliminates the need to configure these settings individually for each nri-bundle sub-chart.