fail validation faster if the image doesn't exist for the right platform

[h4ck3rk3y]

What's your CLI version?

0.79.0

Description & steps to reproduce

MOCK_MEV_IMAGE = "ethpandaops/mock-builder:latest"
MOCK_MEV_SERVICE_NAME = "mock-mev"

def run(plan, args):
launch_mock_mev(plan, "foo", "bar", "doo")

def launch_mock_mev(plan, el_uri, beacon_uri, jwt_secret):
plan.add_service(
name = MOCK_MEV_SERVICE_NAME,
config = ServiceConfig(
image = MOCK_MEV_IMAGE,
ports = {
"rest": PortSpec(number = 18550, transport_protocol="TCP"),
},
cmd = [
"--jwt-secret={0}".format(jwt_secret),
"--el={0}".format(el_uri),
"--beacon={0}".format(beacon_uri)
]
)
)

### Desired behavior


 "ethpandaops/mock-builder:latest" doesn't have arm64 and validation still passes but the execution fails which is confusing. either we override and download despite arch or we fail in validation itself


### What is the severity of this bug?

Painful; this is causing significant friction in my workflow.

[h4ck3rk3y]

Pari from Ethereum ran into this as well