Upgrade SDK to 6.0.100-rc.1.21411.13 (#57143)

Upgrade SDK to 6.0.100-rc.1.21411.13 (#57143)

* Upgrade SDK to 6.0.100-rc.1.21379.2

Both the AzDO and the Core-Eng team believe believe that the issue is on our side and was caused by a thread pool regression. The assumption stands that we need to update to a newer SDK which contains the fix for the thread pool hang.

Pros:
-	AzDO and Core-Eng believe that this will mitigate the AzDO feed restore issues.
Cons:
-	We will upgrade to an unsigned SDK build. Arcade and other repos already did the same to workaround the issue.
-	That SDK build isn’t officially released and won’t until RC 1 ships. This means that developers need to install that build via the nightly channel (from https://github.com/dotnet/installer) if they want to use their globally installed SDK in combination with dotnet/runtime.
-	Even though this is a breaking change, we can’t wait for the next monthly infrastructure rollout.

* set StaticWebAssetsEnabled=false

* Remove IsSupported2 since asserting it is true when it might not be

* Try enabling the runtimeconfig generator everywhere

* Revert part of runtimeconfig parser change

* Fix System.Text.Json tests to run with trimming by setting MetadataUpdaterSupport=true.

Work around SDK issue by overwriting EnableUnsafeUTF7Encoding in System.Text.Encoding

* Disable bundling tests on Mac due to bug

See https://github.com/dotnet/runtime/issues/57242

* Make ProcessInfo tests resilient to RuntimeConfig switches on commandline

* Update global.json

Updating to 6.0.100-rc.1.21411.13

* Update to latest SDK.
Remove System.Text.Encoding.Tests workaround

* ignore runtimeconfig switches _if_ they show up

* Remove test which uses `dotnet run, which is SDK-specific

Co-authored-by: Larry Ewing <lewing@microsoft.com>
Co-authored-by: Eric Erhardt <eric.erhardt@microsoft.com>
Co-authored-by: Andy Gocke <angocke@microsoft.com>
Co-authored-by: John Salem <josalem@microsoft.com>
Co-authored-by: Dan Moseley <danmose@microsoft.com>