Add setup_tools performance metrics to Soong protobuf file.

The setup_tools metrics has been missing since day one and is
needed to track down slowness of setting up the build system.

Bug: b/175706305
Test: m nothing and ran the printproto command to check that the
      setup_tools field has been set.
Change-Id: Idc8a38fa830e0a906170feeede63435715eaa05b