[release/5.0] Make upgrade install new host first, then uninstall old

[ericstj]

Backport of #60307 to release/5.0
Requires dotnet/arcade#8029

Customer Impact

Customers installing upgrades of .NET 5.0 observe the entry for dotnet will move to the end of the PATH variable, often resulting in x86 dotnet being first and winning.

Testing

Manual build of host and upgrade testing. I've tested upgrade scenarios where 5.0 x86 + x64 is installed. Upgrade to 6.0 x64 without the fix will move x64 PATH to end. Once fix is in place we don't move PATH entry.

Risk

Low. This doesn't change installer behavior like some of the other options we considered. The change is scoped to only the host MSI

[ghost]

Tagging subscribers to this area: @Anipik, @safern, @ViktorHofer
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Issue Details

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Backport of #60307 to release/5.0
Requires dotnet/arcade#8029

Customer Impact

Customers installing upgrades of .NET 6.0 observe the entry for dotnet will move to the end of the PATH variable, often resulting in x86 dotnet being first and winning.

Testing

Manual build of host and upgrade testing. I've tested upgrade scenarios where 5.0 x86 + x64 is installed. Upgrade to 6.0 x64 without the fix will move x64 PATH to end. Once fix is in place we don't move PATH entry.

Risk

Low. This doesn't change installer behavior like some of the other options we considered. The change is scoped to only the host MSI

Author:	ericstj
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-

[Anipik]

The drawing test failures are fixed by #60201

[Anipik]

I think @ericstj i jumped the gun here as there were no failures related to the change. I will keep a look out for the arcade update pr. Hopefully i didnt cause any hiccup here.

[ericstj]

That's ok. This was approved over mail. We need to merge all the others and flow arcade.