OCPNODE-4108: add E2E tests for upstream dra-example-driver

[sabujmaity]

Summary

Add hardware-independent DRA end-to-end regression tests using the upstream
dra-example-driver.
No GPU or special hardware required — the driver emulates 9 virtual devices
per node.

JIRA: https://issues.redhat.com/browse/OCPNODE-4108

Test Scenarios

1. Single Device Allocation - DeviceClass + ResourceClaim + Pod lifecycle
2. Resource Cleanup - verifies claim survives pod deletion and is unreserved
3. Multi-Device Allocation - requests 2 devices (skips if < 2 available)
4. Claim Sharing - two pods referencing same claim (handles both outcomes)
5. ResourceClaimTemplate - inline claim creation and automatic cleanup

OpenShift Adaptations

• Grants system:openshift:scc:privileged to driver ServiceAccount
• Applies PSA privileged labels on driver namespace
• Adds control-plane tolerations for SNO scheduling
• Uses image.ShellImage() for proper release payload image mirroring

Verified On

• OpenShift 4.21 SNO cluster
• All 5 tests PASS
• known-image-checker MonitorTest: 0 failures (image mirroring verified)
• go build and go vet clean

Summary by CodeRabbit

• Tests

  • Added a new serial end-to-end suite for the DRA example driver covering device allocation, multi-device scenarios, claim sharing, pod lifecycle/cleanup, and ResourceClaimTemplate behavior; includes device validation, resource builders, and automated prerequisites installer.

• Documentation

  • Added an extended test guide with prerequisites, install/quick-start steps, test commands, OpenShift adaptations, and troubleshooting.

• Chores

  • Registered the example tests with the extended test suite and added OWNERS metadata.