[azure] Standardize Field Names

### Integration Name

Azure Logs [azure]

### Dataset Name

All Azure datasets

### Integration Version

1.23.0

### Agent Version

8.17.4

### OS Version and Architecture

Windows 11

### User Goal

Common fields for all azure logs

### Existing Features

Current fields
`[azure][signinlogs][properties][user_principal_name]`
`[azure][activitylogs][properties][userPrincipalName]`
`[azure][auditlogs][properties][target_resources][0][user_principal_name]`

This is just one example. The field naming do not match up, and are not ECS. If I'm trying to search for a user's principal name (email), it should just be `user.email:user.name@example.com`. Having the fields like this makes searching, discover and dashboards messy.

There are other examples of this.

`[device_detail][display_name]` vs `[deviceDetail][displayName]`
`[device_detail][is_managed]` vs `[deviceDetail][isManaged]`
`[app_display_name]` vs `[appDisplayName]`

There really is no reason to split these logs up into their own sub field (`[azure][signinlogs]` / `[azure][auditlogs]` / etc). `[event][dataset]` already has that covered.

Running `mutate { rename => { "[azure][signinlogs]" => "[azure]" } }` in Logstash to remove the unneeded field names works. However, it has unintended consequence of removing the `[azure][auditlogs][properties]` flattened field.

### What did you see?

I don't have a good example as the user's email address is in the flattened fields and hasn't been pulled out and unable to add it to discover.

### Anything else?

_No response_