[release/6.0] Make UseUrls() override default hosting config

[halter73]

Description

Prior to this change, default config (typically loaded from DOTNET_/ASPNET_ environment variables and command line arguments) could override the application-level configuration. This would prevent GenericWebHostService from seeing the latest configuration set by UseUrls() of DOTNET_URLS, ASPNET_URLS or --urls was set.

Fixes #38185

Customer Impact

This is a big gotcha to customers using WebApplicationBuilder (which is used in all the ASP.NET Core 6 templates) who expect the following to work:

var builder = WebApplication.CreateBuilder(args);
builder.WebHost.UseUrls("http://*:8080");
var app = builder.Build();
app.Run();

A comment on the issue suggesting we patch this has gotten 5 thumbs ups not counting mine.

Regression?

• Yes
• No

[If yes, specify the version the behavior has regressed from]

Risk

• High
• Medium
• Low

This is a small well tested change which only affects the loading of default config sources and those added via a HostFactoryResolver to host configuration.

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

[ghost]

Hi @halter73. If this is not a tell-mode PR, please make sure to follow the instructions laid out in the servicing process document.
Otherwise, please add tell-mode label.

[ghost]

Hi @halter73. Please make sure you've updated the PR description to use the Shiproom Template. Also, make sure this PR is not marked as a draft and is ready-to-merge.

To learn more about how to prepare a servicing PR click here.

[wtgodbe]

/azp run

[wtgodbe]

We can merge this once CI is green & reviewers have signed off

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[halter73]

@davidfowl @Tratcher @captainsafia Can one of you give this a review?

[wtgodbe]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[wtgodbe]

@halter73 this breaks in conjunction with dotnet/runtime#63816 - we're going to revert it for now to unblock builds. Can try again next month when there's more time to react.