[CMake] Fix thread trace sample ENVIRONMENT test property (#544)

Fix thread trace samples set tests properties

[ROCm/rocprofiler-sdk commit: 735b5c3d4a]

projects/rocprofiler-sdk/samples/thread_trace/CMakeLists.txt

@@ -75,5 +75,5 @@ rocprofiler_samples_get_preload_env(PRELOAD_ENV)
 list(APPEND PRELOAD_ENV "ROCPROFILER_TRACE_DECODER_LIB_PATH=${attdecoder_LIB_DIR}")
 
 set_tests_properties(
-    thread-trace-sample PROPERTIES TIMEOUT 60 ENVIRONMENT ${PRELOAD_ENV} LABELS
+    thread-trace-sample PROPERTIES TIMEOUT 60 ENVIRONMENT "${PRELOAD_ENV}" LABELS
                                    "samples;thread-trace" DISABLED ${IS_DISABLED})