Update usage of Ubuntu 20.04 buildtools containers

[mthalman]

Ubuntu 20.04 buildtools containers are EOL: dotnet/dotnet-buildtools-prereqs-docker#1449

References to these images need to be upgraded to a supported version:

• efcore/eng/helix.proj

  Line 20 in 8a8e758

  <HelixTargetQueues Condition = "'$(HelixTargetQueues)' == ''">Windows.10.Amd64.Open;OSX.1200.Amd64.Open;OSX.1200.ARM64.Open;Ubuntu.2204.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-helix-sqlserver-amd64</HelixTargetQueues>

• efcore/azure-pipelines.yml

  Line 233 in 8a8e758

  value: Windows.10.Amd64;OSX.13.Amd64;OSX.13.ARM64;Ubuntu.2204.Amd64@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-helix-sqlserver-amd64

• efcore/azure-pipelines-public.yml

  Line 154 in 8a8e758

  value: Windows.10.Amd64.Open;OSX.13.Amd64.Open;Ubuntu.2204.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-helix-sqlserver-amd64

These changes also need to be backported to the servicing branches.

[AndriySvyryd]

@cincuranet There's currently no replacement image for what was removed in https://github.com/dotnet/dotnet-buildtools-prereqs-docker/pull/1449/files#diff-914793f8af1ec0fbc686ef5e633b615870c02c53ec0dc74159466be650f306c2

We'd need to create a new one, see dotnet/dotnet-buildtools-prereqs-docker#1190

Let me know if you have any questions

[cincuranet]

dotnet/dnceng#5893