Update tool to roll forward to latest major version of runtime installed.

[AraHaan]

This is needed otherwise it will try to require ".NET 2.0 Runtime" to be installed, which will cause roll forward to fail to load 6.0.0's System.Runtime when used on devices with newer versions of the .NET SDK and runtimes.

Fixes: #27660.
Discovered at: #27660 (comment)

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        Summary of the changes
        - Detail 1
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        Fixes #bugnumber

• Tests for the changes have been added (for bug fixes / features) N/A
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[AraHaan]

Welp just tested these changes and it looks like there is 1 more place where it expects ef.dll in .nuget\packages\dotnet-ef\7.0.0-dev\tools\net6.0\any\tools\netcoreapp2.0\any\ 😔

Edit: found it just now.

[AraHaan]

cc: @roji, @ajcvickers does this look good to you on the fix for my issue?

[bricelam]

Most of these changes seem unnecessary and won't actually address the issue you're seeing.

[AraHaan]

The change works.

[AraHaan]

@bricelam I have completed the requested changes and verified that they work still on fixing the issue.

[AraHaan]

Now the github actions check should be rerun and it should pass.

[ajcvickers]

Merged following team review. Cosmos failure was a known issue.

Thanks @AraHaan.