Skip metrics upload when doing benchmarks.

metrics-uploader runs asynchronously, and causes a race condition where
the out dir can't be deleted because metrics uploader is busy in it.

Has the side effect of not polluting the local developer metrics with
benchmark runs too.

Test: treehugger
Change-Id: I7953020cd9c69fb10745facd22648f931fc94477
diff --git a/tools/perf/benchmarks b/tools/perf/benchmarks
index df4c87b..e188858 100755
--- a/tools/perf/benchmarks
+++ b/tools/perf/benchmarks
@@ -335,6 +335,7 @@
                 "--build-mode",
                 "--all-modules",
                 f"--dir={self._options.root}",
+                "--skip-metrics-upload",
             ] + modules
             env = dict(os.environ)
             env["TARGET_PRODUCT"] = lunch.target_product