Secret environment variables cannot be deleted

[justinedelson]

Expected Behaviour

$ aio cloudmanager:set-environment-variables 12345 --secret MY_VAR2 "some secret value"
$ aio cloudmanager:set-environment-variables 12345 --delete MY_VAR2

should result in the environment variable being deleted

Actual Behaviour

setting variables... !
Error: Cannot set variables: https://cloudmanager.adobe.io/api/program/54321/environment/12345/variables (400 Bad Request)
    at res.text.then.text (~/workspaces/projects/aio-cli-plugin-cloudmanager/src/client.js:60:39)

Reproduce Scenario (including but not limited to)

Have a Cloud Service program and environment and an integration with the Deployment Manager role

Steps to Reproduce

See above

Platform and Version

Sample Code that illustrates the problem

Logs taken while reproducing problem