Allow multiple replication jobs at the same time

[yaroslav-gwit]

Right now, the replication function creates a temporary shell script in /tmp/replication.sh, so only 1 replication job can be active at the time (file name is hard coded and file existence is checked before each replication job). HA/Clustered setup requires multiple jobs running at the same time. For this purpose, I am planning to create a /var/run/replication-endpoint-address-hash.sh file.

This way we can still rely on the original design of not trying to "overrun" a currently running operation and fail in some unpredictable way, potentially damaging the data, but at the same time will allow parallel execution to different endpoints.

[yaroslav-gwit]

The change has been implemented by introducing the additional cmd flag --script-name. This allows for more flexibility, but keeps similar safety mechanisms in order to avoid running 2 parallel jobs for the same VM.