Add missing mcg-cli coverage: list buckets

[sagihirshfeld]

The task:
In DFBUGS-822 we found that the following command no longer worked in 4.18:

$ mcg-cli bucket list
INFO[0002] ✅ Exists: NooBaa "noobaa"
INFO[0002] ✅ Exists: Service "noobaa-mgmt"
INFO[0002] ✅ Exists: Secret "noobaa-operator"
INFO[0002] ✅ Exists: Secret "noobaa-admin"
INFO[0003] ✈️  RPC: bucket.list_buckets() Request: <nil>
WARN[0003] RPC: GetConnection creating connection to wss://localhost:60144/rpc/ 0xc000f99f20
INFO[0003] RPC: Connecting websocket (0xc000f99f20) &{RPC:0xc0007ed3b0 Address:wss://localhost:60144/rpc/ State:init WS:<nil> PendingRequests:map[] NextRequestID:0 Lock:{state:1 sema:0} ReconnectDelay:0s cancelPings:<nil>}
INFO[0003] RPC: Connected websocket (0xc000f99f20) &{RPC:0xc0007ed3b0 Address:wss://localhost:60144/rpc/ State:init WS:<nil> PendingRequests:map[] NextRequestID:0 Lock:{state:1 sema:0} ReconnectDelay:0s cancelPings:<nil>}
ERRO[0004] ⚠️  RPC: bucket.list_buckets() Response Error: Code=INVALID_SCHEMA_PARAMS Message=INVALID_SCHEMA_PARAMS SERVER bucket_api#/methods/list_buckets
FATA[0004] INVALID_SCHEMA_PARAMS SERVER bucket_api#/methods/list_buckets 

I found this one by chance, but we need to cover this in OCS-CI so we don't miss future regressions.

Useful references

• A good reference on how to run the mcg-cli command via OCS-CI: cli_get_all_bucket_names. Note that this lists OBCs and not the buckets themselves, so first.bucket would not show here.
• Creating some S3 buckets using the bucket_factory fixture: test_bucket_logs.py#L124-125

[ypersky1980]

This issue is resolved by PR #11046 .