LU-8603 test: Separate tests in metadata_updates

LU-8603 test: Separate tests in metadata_updates

The metadata-updates script is one continuous piece of code
that runs three different tests. These tests need to be broken
out into sub-tests and some of the comments echoed to the
console should be logged.

Test-Parameters: trivial testlist=metadata-updates
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I7e420ee8e0e02d2c2a66ac644301bb457a8b2256
Reviewed-on: https://review.whamcloud.com/24450
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>