[WebToolsE2E][Aspire] Create an aspire 9.0 project and then add an aspire 9.1 project in the same solution and get a warning: "The previously resolved SDK version "9.0.0" will be used and the version "9.1.0" will be ignored".

**INSTALL STEPS**

1. Clean machine: Win11 x64 23h2
2. Install VS 17.13 GA
3. Install the latest Aspire 9.1.0-preview.1.25110.10
- Apply dotnet9 Feed

**REPRO STEPS**

1. Create an Aspire Starter App 9.0 project
2. In the same solution, add an Aspire Starter App 9.1 project

**ACTUAL**
Multiple versions of the same SDK "Aspire.AppHost.Sdk" cannot be specified. The previously resolved SDK version "9.0.0" from location "C:\Users\xxx\source\repos\AspireApp14\AspireApp14.AppHost\AspireApp14.AppHost.csproj" will be used and the version "9.1.0-preview.1.25110.10" will be ignored.

**Workaround:**
- Reopen VS and the warning will disappear

**EXPECTED**
Without any warning