[Multi-Asic Infra]: asic_index gap in single-asic and multi-asic devices

[yejianquan]

Issue Description

For single-asic device, the self.asic_index will be set as 0

sonic-mgmt/tests/common/devices/multi_asic.py

Line 37 in 8b4f733

self.asics = [SonicAsic(self.sonichost, asic_index) for asic_index in self.sonichost.facts[ASICS_PRESENT]]

Sometimes in tests, we compose docker container with the asic_index,
for example, the swss container for asic1(asic_index: 1) will be swss1,
For multi-asic device, the format is f"swss{self.asic_index}"

But the format is not applicable to single-asic,
f"swss{self.asic_index}" -> 'swss0'
but actually the container is 'swss'

This causes the infra and logic to be not compatible between single-asic and multi-asic.
Sample issue: #16314

Results you see

f"swss{self.asic_index}" on single_asic -> swss0
Which != actual value: swss.

Results you expected to see

We should have a compatible function for SonicAsic

class SonicAsic(object):
    def asic_index_for_service(self):
        if self.sonichost.is_multi_asic:
            return self.asic_index
        else:
            return None

then

#Multi-asic
f"swss{sonic_asic.asic_index_for_service()}" = swss0

#Single-asic
f"swss{sonic_asic.asic_index_for_service()}" = swss

Is it platform specific

generic

Relevant log output

No response

Output of show version

No response

Attach files (if any)

No response

[yejianquan]

@sdszhang please help to follow up on this infra enhancement, thanks!