[Build] Don't configure LLDB with tests enabled if the tests will be skipped

Currently the `--skip-test-lldb` flag will only skip *running* the
tests. But we still pass `LLDB_INCLUDE_TESTS` to CMake when configuring
LLDB.

Since swiftlang#66018 configuring LLDB tests will
now always require libcxx to be built. For some presets (e.g.,
`buildbot_osx_package`) we don't need to build libcxx and we explicitly
pass `--skip-test-lldb`; this means if we were to try configure LLDB
tests we would hard error.

The proposed solution is to check whether the user wants to skip LLDB
tests, and if so, set `LLDB_INCLUDE_TESTS=FALSE`.

rdar://109774179

Author: Michael137

Diff for: utils/build-script-impl

@@ -2187,6 +2187,12 @@ for host in "${ALL_HOSTS[@]}"; do
                     DOTEST_ARGS="${DOTEST_ARGS};-E;${DOTEST_EXTRA}"
                 fi
 
+                if [[ "${SKIP_TEST_LLDB}" ]]; then
+                    should_configure_tests="FALSE"
+                else
+                    should_configure_tests=$(false_true ${BUILD_TOOLCHAIN_ONLY})
+                fi
+
                 cmake_options=(
                     "${cmake_options[@]}"
                     -C${LLDB_SOURCE_DIR}/cmake/caches/${cmake_cache}
@@ -2205,7 +2211,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DLLDB_ENABLE_PYTHON=ON
                     -DLLDB_ENABLE_LZMA=OFF
                     -DLLDB_ENABLE_LUA=OFF
-                    -DLLDB_INCLUDE_TESTS:BOOL=$(false_true ${BUILD_TOOLCHAIN_ONLY})
+                    -DLLDB_INCLUDE_TESTS:BOOL="${should_configure_tests}"
                     -DLLDB_TEST_LIBCXX_ROOT_DIR:STRING="${libcxx_build_dir}"
                     -DLLDB_TEST_USER_ARGS="${DOTEST_ARGS}"
                 )