We should have the same behavior for Azure repositories as we have for S3 (see #22762).
Instead of:
```yml
cloud:
azure:
storage:
my_account1:
account: your_azure_storage_account1
key: your_azure_storage_key1
default: true
my_account2:
account: your_azure_storage_account2
key: your_azure_storage_key2
```
Support something like:
```
azure.client:
default:
account: your_azure_storage_account1
key: your_azure_storage_key1
my_account2:
account: your_azure_storage_account2
key: your_azure_storage_key2
```
Then instead of:
```
PUT _snapshot/my_backup3
{
"type": "azure",
"settings": {
"account": "my_account2"
}
}
```
Use:
```
PUT _snapshot/my_backup3
{
"type": "azure",
"settings": {
"config": "my_account2"
}
}
```
If someone uses:
```
PUT _snapshot/my_backup3
{
"type": "azure"
}
```
It will use the `default` azure repository settings.
And mark as deprecated old settings.
Closes#22763.
80b142d218