Disable unit_test for slab allocator

[ROCm/rocshmem commit: 3aaf29399c]

projects/rocshmem/tests/unit_tests/CMakeLists.txt

@@ -77,7 +77,7 @@ target_sources(
     address_record_gtest.cpp
     index_strategy_gtest.cpp
     single_heap_gtest.cpp
-    slab_heap_gtest.cpp
+    #slab_heap_gtest.cpp # Test is disabled because class unused
     symmetric_heap_gtest.cpp
     pow2_bins_gtest.cpp
     remote_heap_info_gtest.cpp