osd: Do not apply log entry if shard not written

osd: Do not apply log entry if shard not written

This was a failed test, where the primary concluded that all objects were present
despite one missing object on the non primary shard.

The problem was caused because the log entries are sent to the unwritten shards if that
shard is missing in order to update the version number in the missing object. However,
the log entry should not actually be added to the log.

Further testing showed there are other scenarios where log entries are sent to
unwritten shards (for example a clone + partial_write in the same transaction),
these scenarios do not want to add the log entry either.

Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>
(cherry picked from commit 24cd772f2099aa5f7dfeb7609522f770d0ae1115)