Alpine319_Offline_PreviousSourceBuiltSdk_x64 fails due to no .NET SDK

[mthalman]

docker run --rm -v /mnt/vss/_work/1/vmr:/vmr -w /vmr -e BUILD_SOURCEVERSION=fba1ff5a76eeeaad47ac82e83fcf2b0a32b6f9bf mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.19-WithNode ./build.sh --clean-while-building --with-sdk /vmr/.dotnet --poison
Custom SDK '/vmr/.dotnet/dotnet' does not exist or is not executable

This is because no previously source built SDK exists. This is shown in the prep scrip results:

++ tar -ozxf /mnt/vss/_work/1/vmr/prereqs/packages/archive/dotnet-sdk-9.0.100-alpha.1.24055.1-alpine.3.19-x64.tar.gz -C /mnt/vss/_work/1/vmr/.dotnet

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

This is due to the update from Alpine 3.17 to Alpine 3.19. We need to re-bootstrap to get a new SDK based on the alpine.3.19 RID.