[tools] added unity suite to known benchmark set

try_perf.py knows now of the "unity" benchmark suite

NOTRY=true

Review-Url: https://codereview.chromium.org/2358873002
Cr-Commit-Position: refs/heads/master@{#39615}

tools/try_perf.py

@@ -49,6 +49,7 @@ PUBLIC_BENCHMARKS = [
   'simdjs',
   'sunspider',
   'sunspider-ignition',
+  'unity',
   'wasm',
 ]