Import-AzAutomationRunbook does not close the input file handle

## Description
When Import-AzAutomationRunbook is called the command does not close the file handle therefore it's not possible to use the same file in subsequent operations. Looks like the problem is at AutomationPSClient.ImportRunbook() line ~624

## Steps to reproduce
Try to publish the same ps1 file to multiple automation accounts in a loop.

## Environment data

```
Name Value
---- -----
PSVersion 7.1.3
PSEdition Core
GitCommitId 7.1.3
OS Microsoft Windows 10.0.22000
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
```

## Module versions

```powershell

```

## Debug output

```

```

## Error output

```

```

Start in AutomationPSClient.ImportRunbook() near line 624 and reproduce the issue by publishing the same .ps1 file to multiple automation accounts in a loop. Trace the input file handle's lifecycle and verify that the file can be reused after each Import-AzAutomationRunbook call.

Written by the indexing model from the issue text.