Allow for Data Centre index snapshots to be created in an alternative location

Problem

Index snapshots are currently stored (and being compressed) on the shared home folder of Confluence Data Center. The compression process uses significant disk I/O, that may affect the cluster performance negatively, possibly causing service degradation.

Proposed solution

Allow administrators of large instances to specify different filesystems for the snapshots, to better manage disk utilization and make sure that packing the index snapshots is performed on a local filesystem (local home).