ninjalog_uploader: Send is_cloudtop=false explicitly

This allows us to distinguish between old data without is_cloudtop
flag and new data from non-Cloudtop.

Bug: 367856712
Change-Id: I01995a050a5780b11465ecd6923e530dff6f7929
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5889398
Reviewed-by: Philipp Wollermann <philwo@google.com>
Auto-Submit: Junji Watanabe <jwata@google.com>
Commit-Queue: Junji Watanabe <jwata@google.com>

ninjalog_uploader.py

@@ -163,6 +163,7 @@ def GetMetadata(cmdline, ninjalog, exit_code, build_duration, user):
         "platform": platform.system(),
         "cpu_core": multiprocessing.cpu_count(),
         "is_cog": gclient_utils.IsEnvCog(),
+        "is_cloudtop": False,
         "build_configs": build_configs,
         "explicit_build_config_keys": explicit_keys,
         "targets": GetBuildTargetFromCommandLine(cmdline),