tests: enable kv_unified to prevent cuda oom error on rtx 2060 (#20645)

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

Author: taronaeo

tests/test-backend-sampler.cpp

@@ -89,6 +89,7 @@ struct test_context {
         cparams.n_batch = 512;
         cparams.samplers = configs.data();
         cparams.n_samplers = configs.size();
+        cparams.kv_unified = true;
 
         // If n_seq_max is not specified, calculate it from configs
         if (n_seq_max < 0) {