LocalTerminologyService should return original FhirOperationException from getExpandedValueSet

[alexzautke]

Describe the bug
In PR #2560 the behaviour of the LocalTerminologyService in ValueSetValidateCode was changed. L179 does not account for the fact that getExpandedValueSet might already return a FhirOperationException with a status code != HTTP 500. The exception handling is too generic here. For example if the ValueSet cannot be found, an HTTP 400 status code will be overwritten.

Expected behavior
Return the original status code to the caller.

Version used:

• FHIR Version: [e.g. R4]
• Version: [5.4.0]

[marcovisserFurore]

This is a regression bug