feat: Azure CNI Overlay support for BYO Subnet

[Bryce-Soghigian]

Fixes #

Description
This PR adds support for BYO subnet for AzureCNI Overlay Clusters. It removes the instance provider subnetID reference and instead resolves the value from launch template parameters.

How was this change tested?

• Additional Test Coverage
• make presubmit

Does this change impact docs?

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

Release Note

Support for Per Nodeclass BYO Subnet

[coveralls]

Pull Request Test Coverage Report for Build 8978512476

Details

• 14 of 14 (100.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.005%) to 97.769%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/cache/unavailableofferings.go	2	95.45%

Totals
Change from base Build 8905676791:	-0.005%
Covered Lines:	36282
Relevant Lines:	37110

---

💛 - Coveralls

[Bryce-Soghigian]

/test

[Bryce-Soghigian]

WARNING: docker_bridge_cidr is not a known attribute of class <class 'azure.mgmt.containerservice.v2024_01_01.models._models_py3.ContainerServiceNetworkProfile'> and will be ignored
ERROR: (EntityStoreOperationError) Failed to save control plane with ID 66398ca8261b450001b56f69. A database operation failed. Please retry later. If this error persists, contact AKS support.
Code: EntityStoreOperationError
Message: Failed to save control plane with ID 66398ca8261b450001b56f69. A database operation failed. Please retry later. If this error persists, contact AKS support.

[Bryce-Soghigian]

Assuming my e2es are failing for unrelated reasons

[Bryce-Soghigian]

/test