Webapp:az appservice plan create failed

**Describe the bug**
I can create a new resource group named `1` both with azure cli and azure portal. While I want an app service plan in this resource group, I failed to create it with azure cli since there is a validator forces me to follow a weird regex pattern.
I try other resources like storage account and succeed create it in the resource group with azure cli and also succeed create a new app service plan in the resource group. I doubt if the validator necessary.

```
> az appservice plan create -g 1 -n testplan
ValidationError: Parameter 'resource_group_name' must conform to the following pattern: '^[-\\w\\._\\(\\)]+[^\\.]$'.
```
**To Reproduce**
Run below command
```
az group create -n 1 -l westus2
az appservice plan create -n test -g 1
az storage account create -n test -g 1
```
**Expected behavior**
App service plan can be created in the resource group `1` just as storage account dose.

**Environment summary**

My cli version:
"azure-cli": "2.15.1",
"azure-cli-core": "2.15.1",
"azure-cli-telemetry": "1.0.6"

Start by reproducing the failure with the listed az group, appservice plan, and storage account commands, then locate the validator for the app service plan's resource_group_name parameter. Compare its pattern with the working storage-account path; done means an app service plan can be created in resource group `1` without weakening valid-name checks.

Written by the indexing model from the issue text.