The current hard-coded value won't work for other distributions not relying on
standard conventions (e.g. nixos...).
This keeps the original behavior and only allow to diverge based on the
environment variable BIN_CASSANDRA [1]
This also fixes an issue on log path inexistence which raises.
Currently trying to run this with my box and this prevents it.
[1] I do not like the name much, I just kept the naming convention from the
LOG_CASSANDRA variable. Although, it's probably fine as it's only for tests.