[llvm] [LLVM-Test] Fix a regression in test dependencies introduced by 0e14973 (PR #161623)

[Rahul Joshi via llvm-commits]

jurahul wrote:

I verified that of the 3 references to `LLVM_TEST_DEPENDS` only the one in `add_lit_testsuites` needs to not have `UnitTests` (already part of https://github.com/llvm/llvm-project/pull/161442) and the other 2 are the ones being updated here to add `UnitTests`.

https://github.com/llvm/llvm-project/pull/161623