Installation Id in `AzureRmContextSettings.json` cannot keep the same with AZ CLI under specific situations

### Description

### Background
After Installing Azure PowerShell, during the first time importing Az.Accounts, we will generate a file called `AzureRmContextSettings.json`.

For the `InstallationId` session in this file, we follow the rules:
- If detected `azconfig.json` generated by AzCLI Installation id, reuse it.
- If not detected, randomly generate a new guid.

By doing so, we can identify the Machines calling AzCLI/ AzPS command by the installation Id.

### Issue
But we have some troubles while trying reusing this id. The Installation Id cannot keep the same with AZ CLI under situations when:
- Under case-sensitive systems, like Lunix/ MacOS.
- User defined a `AZURE_CONFIG_DIR` while installing AzCLI (*).

(*) How AzCLI generate an Installation Id:
- It first checks if the environment variable AZURE_CONFIG_DIR is set.
- If AZURE_CONFIG_DIR is not set, it defaults to ~/.azure/.

### Issue script & Debug output

N/A

### Environment data

N/A

### Module versions

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### Error output

N/A

Start by tracing the first import of Az.Accounts that creates AzureRmContextSettings.json, then compare how it locates the Azure CLI azconfig.json when AZURE_CONFIG_DIR is set and on case-sensitive systems. Done means Azure PowerShell preserves the Azure CLI InstallationId in both described situations, with coverage for those configuration paths.

Written by the indexing model from the issue text.