[Fix](compile) Fix gcc compile on master (#33864)

This is imported by #33511. wrongly used

ColumnStr<T> ();

which violate C++20 standard(see https://wg21.cmeerw.net/cwg/issue2237) but still supported by clang up until now(see llvm/llvm-project#58112)

be/src/pipeline/exec/set_source_operator.cpp

@@ -102,6 +102,7 @@ Status SetSourceOperatorX<is_intersect>::get_block(RuntimeState* state, vectoriz
                                                                     state->batch_size(), eos);
                 } else {
                     LOG(FATAL) << "FATAL: uninited hash table";
+                    __builtin_unreachable();
                 }
             },
             *local_state._shared_state->hash_table_variants);