upload_command_stats: Switch to standard logging module.
upload_command_stats: Switch to standard logging module.

Runs of upload_command_stats were emitting a DEBUG message from cros_build_lib,
because somehow the logging module defaults to the DEBUG level.  I switched
upload_command_status from using "operation" to using "logging", which also
has the effect of setting the logging level to INFO.  That disables the
debug output that looked weird.

BUG=None
TEST=`build_packages --board=x86-generic` still uploads, but without the
debug message from RunGitcommand.
TEST=`upload_command_stats` exits with new error that comes from logging
module.
TEST=`upload_command_stats` exits with new error that comes from logging
module, after propagation from new StatsError exception.

Change-Id: I0c6d040d17169bf211e8331e5066fd74ac3dd85b
Reviewed-on: https://gerrit.chromium.org/gerrit/26057
Tested-by: Matt Tennant <46e612415b446ccde19638e4035892001c237942@chromium.org>
Reviewed-by: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>
Commit-Ready: Matt Tennant <46e612415b446ccde19638e4035892001c237942@chromium.org>

chadversary/chromiumos.chromite,coreos/chromite,zhang0137/chromite,coreos/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite,coreos/chromite