Add configurable total timeout parameter

[jfwm2]

• Since we bumped from v5 to v7 of the Aerospike client the default timeout went from 0 (no timeout) to 1 second.
• This change adds a configuration option to specify this value (total_timeout, e.g. "30s" in the yaml config). The default value is 30s
• We also use explicitly (for readability) 2 retries for the durability checks (read and write policies): this is the default for read (aka. base) policy, while the default for write policiy is 0