1.8-experimental 3: Publishing an msix package influences future builds

### Describe the bug

After publishing an msix file from Visual Studio, the following property is added to the .csproj.user file:

`StoreAndSideload`

This causes the creation of an msix package for every future build from Visual Studio in Release mode. Also, publishing an unpackaged app fails. Workaround is to delete the .csproj.user file or just the added property after publishing.

### Steps to reproduce the bug

1. Publish an msix package of an app with appsdk 1.8 experimental 3 from Visual Studio
2. Build the app from Visual Studio in Release mode
3. Observe than an msix is unnecessarily created in the process
4. Try to publish as an unpackaged app from Visual Studio
5. Observe that this process fails unless the added option is removed from the .csproj.user file

### Expected behavior

_No response_

### Screenshots

_No response_

### NuGet package version

Windows App SDK 1.8 Experimental 2: 1.8.250515001-experimental2

### Packaging type

Packaged (MSIX)

### Windows version

Windows 11 version 24H2 (22621, October 2024 Update)

### IDE

Visual Studio 2022

### Additional context

_No response_

Reproduce the issue in Visual Studio using the .csproj.user file and the UapAppxPackageBuildMode property described in the report. Verify that publishing an MSIX changes later Release builds and unpackaged publishing; done means those later operations no longer require manually deleting the property.

Written by the indexing model from the issue text.