FunctionApp: Upon deleting a service plan, it is not possible to recreate it for same resource group + region

### **This is autogenerated. Please review and update as needed.**

## Describe the bug
Upon deleting a service plan, it is not possible to recreate it for same resource group + region. I have tried redoing it for days after deleting the initial service plan and had to temporarily create one for a different region, i.e. East Asia instead of SoutheastAsia. Currently in QA, but clients will not accept this on production.

**Command Name**
Bug is appearing using 3 means: ARM templates, CLI, manually via Portal.

**Errors:**
"Cannot find Web space rg-big-paceaisph-dev-SoutheastAsiawebspace for subscription 878ee15c-1efd-43de-b6ad-3f7e15338b1d. (Code: NotFound)"
Initially I was getting error of the type 'already exists', then message switched to the above 'cannot find'.
In either case recreation of the service plan, regardless of name, for same RG + Region is impossible.

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- _Put any pre-requisite steps here..._
- ``

## Expected Behavior

## Environment Summary
```
Portal:
subscription: BIG SFA Project (id: 878ee15c-1efd-43de-b6ad-3f7e15338b1d)
resource gr: rg-big-paceaisph-dev

Local:
Windows-10-10.0.17763-SP0
Python 3.6.6
azure-cli 2.0.69 *
Shell: powershell.exe

DevOps Pipelines:
...
```
## Additional Context
We cannot allow ourselves to face this issue on Production.