Revert D147231 "[libc] Adds string and TestLogger classes, use them in LibcTest"

Does not build with gcc.
This reverts commit fc5ae0a7a45bdb5251f3dad3fc07047f987ca447.

GitOrigin-RevId: ebb41f7e3d8ab804e7f0ece9b47741e8812d7c6b
9 files changed