logstash-deb role: support different architectures

[Mullefa]

Recent versions of logstash have architecture-specific downloads (e.g. 7.10.1) compared with older versions (e.g. 7.8.1).

This means that for 7.10.1 you would have to submit e.g. 7.10.1-amd64 as the version number parameter value in the logstash-deb role. Possibly ok 🤷‍♂️ but this does require developers to construct a URI which resolves to the logstash artifact.

Issue can impact developer productivity: since installing logstash on the AMI is typically at the end of the bake, if they aren't aware of this version quirk, it will take ~ time of a bake before they are.