Remove global signal handler for Type remappings

[bctcvai]

When a type is modified a global handler, create_mapping is called which does not isolate the mapping request to the refashioned type.

This has the unintended consequence of potentially leaking risk in an update to unrelated dtypes (or vice versa).

[jrtcppv]

The signal handler would need to be replaced by more surgical modifications to the ES mappings implemented in various REST endpoints.