[baremetal] Changes to `TinkerbellDatacenterConfig.spec` do not get used

**What happened**:
When creating a workload cluster with different values for `TinkerbellDatacenterConfig.spec` than were specified in the creation of the initial management cluster, the values are not getting used. The original values are still used.

https://anywhere.eks.amazonaws.com/docs/getting-started/baremetal/bare-spec/#example-tinkerbelldatacenterconfigspec

**What you expected to happen**:
Changes to `TinkerbellDatacenterConfig.spec` should work.

**How to reproduce it (as minimally and precisely as possible)**:

**Anything else we need to know?**:

**Environment**:
- EKS Anywhere Release:
- EKS Distro Release:

Start with the linked bare-metal TinkerbellDatacenterConfig.spec example and trace how management-cluster values are reused when a workload cluster is created. Reproduce the case with different spec values, then identify the relevant reconciliation entry point and add coverage showing that the workload cluster uses its updated values.

Written by the indexing model from the issue text.