Revert "llvmPackages.tblgen: add missing lldb-tblgen"

Breaks Darwin bootstrap:

    CMake Error at /tmp/nix-build-llvm-tblgen-19.1.7.drv-0/llvm-tblgen-src-19.1.7/lldb/test/CMakeLists.txt:197 (message):
      LLDB test suite requires libc++, but it is currently disabled.  Please add
      `libcxx` to `LLVM_ENABLE_RUNTIMES` or disable tests via
      `LLDB_INCLUDE_TESTS=OFF`.

It’s probably not too hard to fix but I don’t really understand the
details of this derivation and it’s blocking Darwin `stdenv` builds
with a few days to go until the next cycle, so reverting for now.

This reverts commit d175d8a4c5.

pkgs/development/compilers/llvm/common/tblgen.nix

@@ -50,7 +50,6 @@ let
           cp -r ${monorepoSrc}/clang "$out"
           cp -r ${monorepoSrc}/clang-tools-extra "$out"
           cp -r ${monorepoSrc}/mlir "$out"
-          cp -r ${monorepoSrc}/lldb "$out"
         ''
       )
     else
@@ -87,7 +86,6 @@ let
             "llvm"
             "clang"
             "clang-tools-extra"
-            "lldb"
           ]
           ++ lib.optionals (lib.versionAtLeast release_version "16") [
             "mlir"
@@ -101,7 +99,6 @@ let
       [
         "clang-tblgen"
         "llvm-tblgen"
-        "lldb-tblgen"
       ]
       ++ lib.optionals (lib.versionAtLeast release_version "15") [
         "clang-tidy-confusable-chars-gen"
@@ -117,10 +114,6 @@ let
 
     installPhase = ''
       mkdir -p $out
-
-      # Remove useless files
-      rm -f bin/{lldb-dotest,lldb-repro,llvm-lit,update_core_linalg_named_ops.sh}
-
       cp -ar bin $out/bin
     '';
   });