Refactor aws_io_setup class - specifically, the IO values per instance

[mykaul]

My eyes hurt from seeing so many `elif'. See

scylla-machine-image/common/scylla_cloud_io_setup

Line 41 in ad01b2a

def generate(self):

We should store this in a dictionary, JSON or whatnot. Single location preferably.

[mykaul]

Part of this (I should open a separate issue for it!) is that we need to validate the numbers are still real. Ref https://github.com/scylladb/scylla-enterprise/issues/4713#issuecomment-2367619463
We do have a job that is testing a wide range of instances, it should probably compare the results and the hard-coded values (CC @roydahan )

[roydahan]

I created a separate issue for the above comment in qa-tasks.

[roydahan]

My eyes hurt from seeing so many `elif'. See

scylla-machine-image/common/scylla_cloud_io_setup

Line 41 in ad01b2a

def generate(self):

We should store this in a dictionary, JSON or whatnot. Single location preferably.

Hurt is understatement.
@yaronkaikov a dictionary is the simplest and quickest solution.