feat: ListNodeImageVersions + shared image gallery support

[Bryce-Soghigian]

Fixes #

Description
This pr introduces

1. USE_SIG option that is used to control if we should or should not use shared image galleries
2. Shared Image Gallery ID Resolution
3. New ListNodeImageVersions logic for getting the latest approved agentbaker node image version rather than using galleries as a source of truth

Open Qs:
Are we ok with all Nodes with Community Image gallery node images being drifted over to use SIG in managed karpenter with this change?
Should we implement the windows side changes too for the NodeImageVersions api?

How was this change tested?

• manual testing on MSFT Tenant SIG Galleries for Ubuntu and Azure Linux
• make az-all
• make test

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

Release Note

[coveralls]

Pull Request Test Coverage Report for Build 12442803767

Details

• 147 of 202 (72.77%) changed or added relevant lines in 13 files are covered.
• 5 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.06%) to 95.42%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/providers/imagefamily/types.go	8	12	66.67%
pkg/providers/imagefamily/image.go	41	47	87.23%
pkg/providers/instance/azure_client.go	1	7	14.29%
pkg/providers/imagefamily/nodeimageversionsclient.go	36	75	48.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/cloudprovider/drift.go	1	57.14%
pkg/providers/instance/azure_client.go	1	15.0%
pkg/providers/imagefamily/image.go	1	83.15%
pkg/fake/pricingapi.go	2	92.31%

Totals
Change from base Build 12438947198:	-0.06%
Covered Lines:	48132
Relevant Lines:	50442

---

💛 - Coveralls

[tallaxes]

Pease resolve merge conflicts (which should include removal of AKSNodeClass imageVersion)

[Copilot]

Copilot reviewed 5 out of 19 changed files in this pull request and generated 1 suggestion.

Files not reviewed (14)

• Makefile-az.mk: Language not supported
• pkg/providers/imagefamily/image_test.go: Evaluated as low risk
• pkg/cloudprovider/drift.go: Evaluated as low risk
• pkg/test/options.go: Evaluated as low risk
• pkg/fake/nodeimageversionsapi.go: Evaluated as low risk
• pkg/providers/instancetype/suite_test.go: Evaluated as low risk
• pkg/providers/instance/instance.go: Evaluated as low risk
• pkg/providers/instance/azure_client.go: Evaluated as low risk
• pkg/test/environment.go: Evaluated as low risk
• karpenter-values-template.yaml: Evaluated as low risk
• pkg/providers/imagefamily/azlinux.go: Evaluated as low risk
• pkg/operator/operator.go: Evaluated as low risk
• pkg/providers/imagefamily/ubuntu_2204.go: Evaluated as low risk
• pkg/providers/imagefamily/types.go: Evaluated as low risk

Comments skipped due to low confidence (1)

pkg/providers/imagefamily/image.go:132

• Ensure that the new string splitting approach correctly handles all possible cases by adding test cases.

imageID, ok := p.imageCache.Get(key)

[tallaxes]

Everything looks good and ready to go (caching may be further simplified, I think, but that's minor), but E2E tests are failing:

https://github.com/Azure/karpenter-provider-azure/actions/runs/12309122786/job/34355672677

Error: variable ${SIG_SUBSCRIPTION_ID} not set

[tallaxes]

@Bryce-Soghigian please link to evidence of E2E tests passing

[Bryce-Soghigian]

@tallaxes

We can see the utilization + ACR tests are selecting v6 skus, which as we have been over this functionality is currently broken. 
See: https://github.com/Azure/karpenter-provider-azure/actions/runs/12361732672/job/34731291609#step:18:130, https://github.com/Azure/karpenter-provider-azure/actions/runs/12361732672/job/34731292840#step:18:318
---

Updating the branch to include your fix to that bug and will rerun the e2es 

[tallaxes]

🎉 E2E: https://github.com/Azure/karpenter-provider-azure/actions/runs/12439573149

(Please follow up with including NVMe-only VM SKUs when Shared Image Gallery is used.)

[tallaxes]

Please follow up with #617 (comment) (could be separate PR)