IMPALA-7157: Avoid unnecessarily pretty printing profiles per fragment instance
IMPALA-7157: Avoid unnecessarily pretty printing profiles per fragment instance

In SendReport(), if VLOG_FILE_IS_ON is 'true' (which is not the most
verbose logging level, but is higher than default), we pretty print
the profile for every fragment instance, which is a very expensive
operation, as serializing the profile is non-trivial (look at
RuntimeProfile::PrettyPrint()), and printing large amounts of information
to the logs isn't cheap as well. Lastly, it is very noisy.

This seems unnecessary since this will not benefit us, as all the
profiles are merged at the coordinator side. We could argue that this
might be necessary when an executor fails to send the profile to the
coordinator, but that signifies a network issue which will not be
reflected in the profile of any fragment instance.

This will help reduce noise in the logs when the log level is
bumped up to find other real issues that VLOG_FILE can help with.

Change-Id: Ic0445950385fa6160764feaed9a993fa0e59b242
Reviewed-on: http://gerrit.cloudera.org:8080/10669
Reviewed-by: Sailesh Mukil <a0dfbcae8e92bb4f48772d8c6743e175570f6f74@cloudera.com>
Tested-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>

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