bench: remove env-gate from benchmark groups, cut NUM_ITERS to 1000

Benchmark groups 1-5 now run unconditionally in CI (~9s total).
Env-gates moved to separate PR PaddlePaddle#7170.

Author: cloudforge1

tests/spec_decode/test_benchmark_ngram_kernel.py

@@ -40,7 +40,7 @@
 
 MAX_NGRAM_SIZE = 3
 MAX_DRAFT_TOKENS = 10
-NUM_ITERS = 10000
+NUM_ITERS = 1000
 WARMUP = 5
 
 
@@ -206,10 +206,6 @@ def _print_table(title, header, rows):
     print(f"{'=' * 80}")
 
 
-@unittest.skipUnless(
-    os.environ.get("RUN_NGRAM_BENCHMARKS", "0") == "1",
-    "Set RUN_NGRAM_BENCHMARKS=1 to run multi-group profiling (slow)",
-)
 class TestNgramBenchmarkGroups(unittest.TestCase):
     """Multi-dimension benchmark matching NKNaN's 5-group methodology."""