'--subscription' sometimes exists sometimes not

**Related command**
`az account alias xxx`
`az webapp xxx`

**Describe the bug**
I am using the python code to get all the help information of commands. I find that a global parameter '--subscription' sometimes exists sometimes not. **This happens in (all?) commands from extension 'account' and 'webapp'.**

**To Reproduce**
Install azure-cli and extension 'account', run the following python code. Code is easy. It loads all the commands and see if commands 'az account alias create' has parameter '--subscription' and run it 10 times.
```
from azure.cli.core import MainCommandsLoader, AzCli
from azure.cli.core.commands import AzCliCommandInvoker
from azure.cli.core.parser import AzCliCommandParser
from azure.cli.core.file_util import create_invoker_and_load_cmds_and_args, get_all_help
from azure.cli.core._help import AzCliHelp

for i in range(10):
az_cli = AzCli(cli_name='az',
commands_loader_cls=MainCommandsLoader,
invocation_cls=AzCliCommandInvoker,
parser_cls=AzCliCommandParser,
help_cls=AzCliHelp)
create_invoker_and_load_cmds_and_args(az_cli)
help_files = get_all_help(az_cli)
command_alias_create = next((h for h in help_files if h.command == 'account alias create'), None)
print(f"[Note] 'account alias create' has {len(command_alias_create.parameters)} parameters")
print(f"[Note] 'account alias create' contains '--subscription': {'--subscription' in (p.name for p in command_alias_create.parameters)}")
```
This is the output in my side. Sometimes command 'az account alias create' has 14 parameters with '--subscription', sometimes it has 13 parameters without '--subscription'.

**Expected behavior**
The output should always be the same (always has '--subscription' or not).

**Environment summary**
```
Python 3.9.7
{
"azure-cli": "2.35.0",
"azure-cli-core": "2.35.0",
"azure-cli-telemetry": "1.0.6",
"extensions": {
"account": "0.2.2",
"acrtransfer": "1.1.0",
"ad": "0.1.0",
"aem": "0.3.0",
"ai-examples": "0.2.5",
"aks-preview": "0.5.63",
"alertsmanagement": "0.2.2",
"alias": "0.5.2",
"amg": "0.1.0",
"application-insights": "0.1.16",
"appservice-kube": "0.1.6",
"arcappliance": "0.2.18",
"arcdata": "1.3.1",
"attestation": "0.2.0",
"authV2": "0.1.1",
"automation": "0.1.1",
"azure-batch-cli-extensions": "6.0.0",
"azure-cli-ml": "1.37.0",
"azure-devops": "0.25.0",
"azure-firewall": "0.13.0",
"azure-iot": "0.14.0",
"azurestackhci": "0.2.3",
"baremetal-infrastructure": "1.0.0",
"blockchain": "0.1.1",
"blueprint": "0.3.1",
"cli-translator": "0.3.0",
"cloud-service": "0.2.0",
"communication": "1.1.0",
"confidentialledger": "0.1.0",
"confluent": "0.4.0",
"connectedk8s": "1.2.8",
"connectedmachine": "0.4.1",
"connectedvmware": "0.1.6",
"containerapp": "0.3.1",
"cosmosdb-preview": "0.15.0",
"costmanagement": "0.2.1",
"csvmware": "0.3.0",
"custom-providers": "0.2.1",
"customlocation": "0.1.3",
"databox": "0.1.3",
"databricks": "0.8.0",
"datadog": "0.1.1",
"datafactory": "0.5.0",
"datamigration": "0.3.0",
"dataprotection": "0.3.0",
"datashare": "0.2.0",
"db-up": "0.2.7",
"deploy-to-azure": "0.2.0",
"desktopvirtualization": "0.2.0",
"dev-spaces": "1.0.6",
"diskpool": "0.2.0",
"dms-preview": "0.15.0",
"dnc": "0.1.3",
"edgeorder": "0.1.0",
"elastic": "0.1.0",
"enterprise-edge": "0.1.1",
"eventgrid": "0.4.9",
"express-route-cross-connection": "0.1.1",
"footprint": "1.0.0",
"front-door": "1.0.16",
"functionapp": "0.1.1",
"fzf": "1.0.2",
"guestconfig": "0.1.1",
"hack": "0.4.3",
"hardware-security-modules": "0.1.0",
"healthbot": "0.1.0",
"healthcareapis": "0.3.4",
"hpc-cache": "0.1.5",
"image-copy-extension": "0.2.9",
"image-gallery": "0.1.3",
"import-export": "0.1.1",
"init": "0.1.0",
"interactive": "0.4.5",
"internet-analyzer": "0.1.0rc6",
"ip-group": "0.1.2",
"k8s-configuration": "1.5.1",
"k8s-extension": "1.2.0",
"k8sconfiguration": "0.2.4",
"kusto": "0.5.0",
"log-analytics": "0.2.2",
"log-analytics-solution": "0.1.1",
"logic": "0.1.5",
"logz": "0.1.0",
"maintenance": "1.3.0",
"managementpartner": "0.1.3",
"mesh": "0.10.7",
"mixed-reality": "0.0.4",
"ml": "2.2.3",
"monitor-control-service": "0.3.0",
"netappfiles-preview": "0.3.2",
"next": "0.1.2",
"notification-hub": "0.2.0",
"offazure": "0.1.0",
"peering": "0.2.1",
"portal": "0.1.2",
"providerhub": "0.2.0",
"purview": "0.1.0",
"quantum": "0.15.0",
"quota": "0.1.0",
"rdbms-connect": "1.0.2",
"redisenterprise": "0.1.1",
"resource-graph": "2.1.0",
"resource-mover": "0.1.1",
"sap-hana": "0.6.5",
"scheduled-query": "0.5.0",
"scvmm": "0.1.4",
"sentinel": "0.1.2",
"serial-console": "0.1.1",
"spring-cloud": "3.1.3",
"ssh": "1.1.1",
"stack-hci": "0.1.4",
"storage-blob-preview": "0.6.1",
"storage-preview": "0.8.2",
"storagesync": "0.1.2",
"stream-analytics": "0.1.2",
"subscription": "0.1.4",
"support": "1.0.3",
"timeseriesinsights": "0.2.1",
"virtual-network-manager": "0.5.0",
"virtual-network-tap": "0.1.0",
"virtual-wan": "0.2.11",
"vm-repair": "0.4.3",
"vmware": "4.0.2",
"webapp": "0.4.0",
"webpubsub": "1.1.0"
}
}
```

**Additional context**
I am using this information to generate the Docs Page(https://docs.microsoft.com/en-us/cli/azure/account/alias?view=azure-cli-latest) . Currently I have to hard-code the global parameters for all commands because of this issue.