This is a new extention of ObjectName that uses less memory.
TableMetricNameFactory and AllTableMetricNameFactory can
create it instead of regular ObjectName to save memory.
It is possible to save memory because each name created by
TableMetricNameFactory (or AllTableMetricNameFactory) shares
most of its data with other names created by the same factory
and there's no need to create multiple copies.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
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