Editing existing job schedule destroy its JSON content

**Describe the bug**
When editing the existing job schedule the app will not retrieve full JSON content from the batch service account. This results lost of the existing job schedule configuration after editing the job schedule. Particularly the `commonEnvironmentSettings` template element will be deleted from the job schedule configuration. This breaks batch service execution.

**Expected behavior**
The app should not destroy an existing configuration of the job schedule particularly its `commonEnvironmentSettings` section.

**Version (please complete the following information):**
- OS: Mac OS 11.2.3 (20D91)
- Version 2.8.0-stable.484 (2.8.0-stable.484.484)