Enhance test coverage of SetProviderID function in machine.go

[Prajyot-Parab]

/kind feature
/area provider/ibmcloud

Describe the solution you'd like
[A clear and concise description of what you want to happen.]

• Enhance test coverage of SetProviderID function in machine.go

Ref - https://github.com/kubernetes-sigs/cluster-api-provider-ibmcloud/blob/main/cloud/scope/machine.go#L1077-L1085

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

• This is required to fix the test case failures reported post removal of deprecated v1 provider id format.

[Prajyot-Parab]

/cc @Karthik-K-N

[arshadd-b]

/assign