Use branded triplet in llvm build on AZL 4.0

[am11]

Removed the workaround and match packages' approach to use branded triplet, per #1733 (comment).

[am11]

cc @akoeplinger

[akoeplinger]

Thank you!

[am11]

@akoeplinger, unfortunately, this is not enough. The symlink approach is much simpler than the "matching distro" approach. The symlink is one line vs. this microsoft/azurelinux@f394783. They manually create /etc/clang/{triple}.cfg (which you can check after dnf install, as you did before), then point the LLVM build to use that config file. In our case, that would mean echo .... > /etc/clang/{triple}.cfg followed by COPY in the other layer, which is a bit more work than the symlink. It's all distro-specific branding that has zero bearing on the product. Honestly, it doesn't make much sense to follow distro branding here; if anything, it should be dotnet branding since this is our custom llvm toolchain build.