llama : enable LLAMA_SET_ROWS=1 by default (#14959)

ggml-ci

src/llama-kv-cache-unified.h

@@ -230,7 +230,7 @@ private:
 
     // env: LLAMA_SET_ROWS (temporary)
     // ref: https://github.com/ggml-org/llama.cpp/pull/14285
-    bool supports_set_rows = false;
+    bool supports_set_rows = true;
 
     const llama_swa_type swa_type = LLAMA_SWA_TYPE_NONE;