E2E test process not guaranteed to be running

[westin-m]

on .net9 target frameworks the web UI tests do not launch.

The WebAppUiTests.WebAppCallsApiCallsGraphLocally.ChallengeUser_MicrosoftIdFlow_LocalApp_ValidEmailPasswordCreds_CallsDownStreamApiWithCiamAsync test is failing in OneBranch builds because myWebApp.exe is exiting prematurely.

Repro:
In WebAppUiTests, add net9.0 target framework:
<TargetFrameworks>net8.0; net9.0</TargetFrameworks>
Rebuild.
In the test explorer, run the .net 9 tests, and it will fail:

the UI automation failed: System.ComponentModel.Win32Exception (2): An error occurred trying to start process 'D:\git\idWeb\tests\DevApps\ciam\myWebApi\bin\Debug\net9.0\myWebApi.exe' with working directory 'D:\git\idWeb\tests\DevApps\ciam\myWebApi\bin\Debug\net9.0'. The system cannot find the file specified.

same repros w/ the B2C tests and in the build.