blackbox-prober-0.1.30: Add configurable total timeout parameter

  - 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