[llvm-branch-commits] [lit] Remove support for %T (PR #160028)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/160028

This patch removes support for %T from llvm-lit. For now we mark the
test unresolved and add an error message noting the substitution is
deprecated. This is exactly the same as the error handling for other
substitution failures. We intend to remove support for the nice error
message once 22 branches as users should have moved over by the they are
upgrading to v23.