Automerge: Revert "[clangd] Enable lit internal shell by default (#170186)"

This reverts commit 671a8ce.

This stil broke the clangd-ubuntu-tsan bot. It seems like somehow the
PATH variable is not getting propagated in the
system-include-extractor.test test.

Author: boomanaiden154

clang-tools-extra/clangd/test/lit.cfg.py

@@ -1,28 +1,14 @@
-import os
-import shutil
-
 import lit.llvm
 import lit.util
 
 lit.llvm.initialize(lit_config, config)
 lit.llvm.llvm_config.clang_setup()
 lit.llvm.llvm_config.use_default_substitutions()
 
-# TODO: Consolidate the logic for turning on the internal shell by default for all LLVM test suites.
-# See https://github.com/llvm/llvm-project/issues/106636 for more details.
-#
-# We prefer the lit internal shell which provides a better user experience on failures
-# and is faster unless the user explicitly disables it with LIT_USE_INTERNAL_SHELL=0
-# env var.
-use_lit_shell = True
-lit_shell_env = os.environ.get("LIT_USE_INTERNAL_SHELL")
-if lit_shell_env:
-    use_lit_shell = lit.util.pythonize_bool(lit_shell_env)
-
 config.name = "Clangd"
 config.suffixes = [".test"]
 config.excludes = ["Inputs"]
-config.test_format = lit.formats.ShTest(not use_lit_shell)
+config.test_format = lit.formats.ShTest(not lit.llvm.llvm_config.use_lit_shell)
 config.test_source_root = config.clangd_source_dir + "/test"
 config.test_exec_root = config.clangd_binary_dir + "/test"
 
@@ -55,13 +41,6 @@ def calculate_arch_features(arch_string):
 if lit.util.pythonize_bool(config.have_benchmarks):
     config.available_features.add("have-benchmarks")
 
-# This is needed to avoid running a single test (system-include-extractor.test)
-# on a single buildbot (clangd-ubuntu-tsan) and likely should not be needed. We
-# are able to unconditionally assume a chmod binary exists for check-llvm.
-# TODO(boomanaiden154): Fix this after investigating the bot setup.
-if shutil.which("chmod"):
-    config.available_features.add("chmod")
-
 # It is not realistically possible to account for all options that could
 # possibly be present in system and user configuration files, so disable
 # default configs for the test runs.

clang-tools-extra/clangd/test/system-include-extractor.test

@@ -1,7 +1,7 @@
 # RUN: rm -rf %t.dir && mkdir -p %t.dir
 
 # The mock driver below is a shell script:
-# REQUIRES: shell, chmod
+# REQUIRES: shell
 
 # Create a bin directory to store the mock-driver and add it to the path
 # RUN: mkdir -p %t.dir/bin