AI 148675: CTS: Copy only the 'startcts' script into the cts distribution

  Before CL 148645, 'startcts' called the 'cts' script. This is no longer the
  case, so we want to exclude the 'cts' script from the distribution to avoid
  confusion. The 'cts' script is only used when running cts directly on a
  fully built source tree.

Automated import of CL 148675