[tools] Cleanup spirv-sim

spirv-sim was supposed to be used to test cross-lane interactions.
This utility was in the end never used for testing, and as we move to
proper end-to-end testing through the llvm/offload-test-suite project,
this becomes obsolete.

Cleaning this up.

Author: Keenuts

llvm/test/CodeGen/SPIRV/lit.local.cfg

@@ -1,16 +1,6 @@
 if not "SPIRV" in config.root.targets:
     config.unsupported = True
 
-spirv_sim_root = os.path.join(config.llvm_src_root, "utils", "spirv-sim")
-
-config.substitutions.append(
-    (
-        "spirv-sim",
-        "'%s' %s" % (config.python_executable,
-                     os.path.join(spirv_sim_root, "spirv-sim.py")),
-    )
-)
-
 if config.spirv_tools_tests:
     config.available_features.add("spirv-tools")
     config.substitutions.append(("spirv-dis", os.path.join(config.llvm_tools_dir, "spirv-dis")))