Description of problem:
Memory threshold change of C&U Data Collectors/Refresh Workers in UI does not work.

How reproducible:
Always on 5.11.2 (5.11.2.2.20200130212511_3ed31dc)

Steps to Reproduce:
1. Navigate to Configuration -> Settings -> (appliance) -> Workers
2. Change Refresh worker Memory threshold to 1.1 GB
3. Save the changes
4. Refresh the page

Actual results:
1.
2.
3.
4. Refresh worker memory threshold is 2 GB (previous value)

Expected results:
1.
2.
3.
4. Refresh worker memory threshold is 1.1 GB

Additional info:
Works in 5.10.14 (5.10.14.0.20200107223945_aa73a61)

1.
2.
3.
4. In AS (Advanced settings tab), names according to UI ones are:
UI: C & U Data Collectors  -> AS: ems_metrics_collector_worker
UI: Refresh -> AS: ems_refresh_worker

Action in UI created memory_threshold of ems_refresh_worker,
but memory threshold in :defaults is used and displayed in UI anyways.
In 5.10, change in UI changed the defaults memory_threshold value.
Changing that :defaults:memory_threshold value manually in Advanced Settings triggers the expected change in UI.

Snippet of Advanced Settings:
:ems_refresh_worker:
        :ems_refresh_worker_amazon: {}
        :ems_refresh_worker_amazon_network: {}
        ...
        :defaults:
          :memory_threshold: 2.gigabytes <-- this should be changed
          :nice_delta: 7
          :poll: 10.seconds
          :poll_method: :normal
          :queue_timeout: 120.minutes
          :dequeue_method: :sql
        ...
        :memory_threshold: 1.1.gigabytes <-- new created atribute (bug)

This applies for C & U Data Processors and Refresh on Workers page only, changes of memory thresholds of other Workers work as expected.