IIS Express: "HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process" if site contains multiple asp.net core applications

### Describe the bug
If IIS express site has mulitple asp.net core applications only first started application would work correctly. second started application would return "HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process" error. Each iis application has its own application pool.

### To Reproduce
1. pull https://github.com/KosValiev/AspNetCoreIIsExpress
2. Execute .\buildAndRun.ps1
3. Execute in newly opened powershell console `Invoke-WebRequest 'http://localhost:44333/site2/weatherforecast'`

`StatusCode : 200
StatusDescription : OK
Content : [{"date":"2021-04-06T22:22:39.7741679+03:00","temperatureC":-6,"temperatureF":22,"summary":"Cool"},
{"date":"2021-04-07T22:22:39.7741721+03:00","temperatureC":22,"temperatureF":71,"summary":"Chilly"}
,{...
RawContent : HTTP/1.1 200 OK
X-SourceFiles: =?UTF-8?B?QzpccHJvamVjdHNcQXNwTmV0Q29yZUlJc0V4cHJlc3Ncc3JjXEFzcE5ldENvcmVJSXNFeHByZX
NzLlNpdGUyXGJpblxEZWJ1Z1xuZXQ1LjBcd2VhdGhlcmZvcmVjYXN0?=
Content-Length: 500
Conte...
Forms : {}
Headers : {[X-SourceFiles, =?UTF-8?B?QzpccHJvamVjdHNcQXNwTmV0Q29yZUlJc0V4cHJlc3Ncc3JjXEFzcE5ldENvcmVJSXNFeHBy
ZXNzLlNpdGUyXGJpblxEZWJ1Z1xuZXQ1LjBcd2VhdGhlcmZvcmVjYXN0?=], [Content-Length, 500], [Content-Type,
application/json; charset=utf-8], [Date, Mon, 05 Apr 2021 19:22:39 GMT]...}
Images : {}
InputFields : {}
Links : {}
ParsedHtml : mshtml.HTMLDocumentClass
RawContentLength : 500`

4. Execute `Invoke-WebRequest 'http://localhost:44333/site1/weatherforecast'`

#### Actual result
`Invoke-WebRequest : HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process
Common solutions to this issue:
Select a different application pool to create another in-process application.
Troubleshooting steps:
Check the system event log for error messages
Enable logging the application process' stdout messages
Attach a debugger to the application process and inspect
For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028526`

#### Expectd result
`StatusCode : 200
StatusDescription : OK
Content : [{"date":"2021-04-06T22:22:39.7741679+03:00","temperatureC":-6,"temperatureF":22,"summary":"Cool"},
{"date":"2021-04-07T22:22:39.7741721+03:00","temperatureC":22,"temperatureF":71,"summary":"Chilly"}
,{...
RawContent : HTTP/1.1 200 OK
X-SourceFiles: =?UTF-8?B?QzpccHJvamVjdHNcQXNwTmV0Q29yZUlJc0V4cHJlc3Ncc3JjXEFzcE5ldENvcmVJSXNFeHByZX
NzLlNpdGUyXGJpblxEZWJ1Z1xuZXQ1LjBcd2VhdGhlcmZvcmVjYXN0?=
Content-Length: 500
Conte...
Forms : {}
Headers : {[X-SourceFiles, =?UTF-8?B?QzpccHJvamVjdHNcQXNwTmV0Q29yZUlJc0V4cHJlc3Ncc3JjXEFzcE5ldENvcmVJSXNFeHBy
ZXNzLlNpdGUyXGJpblxEZWJ1Z1xuZXQ1LjBcd2VhdGhlcmZvcmVjYXN0?=], [Content-Length, 500], [Content-Type,
application/json; charset=utf-8], [Date, Mon, 05 Apr 2021 19:22:39 GMT]...}
Images : {}
InputFields : {}
Links : {}
ParsedHtml : mshtml.HTMLDocumentClass
RawContentLength : 500`

### Further technical details
C:\Windows\System32>dotnet --info
.NET Core SDK (reflecting any global.json):
Version: 5.0.104
Commit: ca6b6acadb

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18363
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\5.0.104\

Host (useful for support):
Version: 5.0.4
Commit: f27d337295

.NET SDKs installed:
3.1.100 [C:\Program Files\dotnet\sdk]
3.1.113 [C:\Program Files\dotnet\sdk]
5.0.101 [C:\Program Files\dotnet\sdk]
5.0.104 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.All 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 3.1.13 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 5.0.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]