exit code from zbctl not handed through

[grexe]

Note: I wrongly attributed this bug to zbctl itself, but there it works (when invoking the shell executable from the distribution): camunda/zeebe#3993

When invoking zbctl with invalid arguments, or Zeebe is not running at all, it still exits with code 0, which is wrong and makes it hard to integrate in scripts.

E.g.:

❯ zbctl --insecure status

Error: rpc error: code = Unavailable desc = connection error: desc = "transport: Error while dialing dial tcp 127.0.0.1:26500: connect: connection refused"
Usage:
…

❯ echo $?
0

In original zbctl, you get 1 in this case.