88085: workload/schemachanger: re-enable the schema changer workload r=fqazi a=fqazi

Previously the schema changer workload was disabled because of two intermittent issues:

1.  The workload itself had an issue due to a recent refactor that did not properly detect/handle potential execution errors.  While the set of errors was generated it was never used properly in some cases after a recent refactor
2. Some scenarios involving inserts could fail binding OID's inside the resolveOID code path, specifically this code path does not properly handle dropped descriptors. These changes enforces the old behaviour where the resolution should just *fail*.

Co-authored-by: Faizan Qazi <[email protected]>