do not switch client on listing entities per zone

[arthuraliiev]

Description

Avoid redundant calls to list-zones

Checklist

(For exoscale contributors)

• Changelog updated (under Unreleased block)
• Testing

Testing

EXOSCALE_TRACE=1 go run main.go compute deploy-target list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-deploy-targets
>>> Operation: list-deploy-targets
>>> Operation: list-deploy-targets
>>> Operation: list-deploy-targets

=======

EXOSCALE_TRACE=1 go run main.go compute elastic-ip list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-elastic-ips
>>> Operation: list-elastic-ips
>>> Operation: list-elastic-ips
>>> Operation: list-elastic-ips

=======

EXOSCALE_TRACE=1 go run main.go compute instance list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-instances
>>> Operation: list-instances
>>> Operation: list-instances
>>> Operation: list-instances
>>> Operation: get-instance-type
>>> Operation: get-instance-type

=======

EXOSCALE_TRACE=1 go run main.go compute instance snapshot list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-snapshots
>>> Operation: list-snapshots
>>> Operation: list-snapshots
>>> Operation: list-snapshots
>>> Operation: get-instance

=======

EXOSCALE_TRACE=1 go run main.go compute instance list -z ch-gva-2 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-instances
>>> Operation: get-instance-type
>>> Operation: get-instance-type

=======

EXOSCALE_TRACE=1 go run main.go compute instance-pool list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-instance-pools
>>> Operation: list-instance-pools
>>> Operation: list-instance-pools
>>> Operation: list-instance-pools

=======

EXOSCALE_TRACE=1 go run main.go compute load-balancer list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-load-balancers
>>> Operation: list-load-balancers
>>> Operation: list-load-balancers
>>> Operation: list-load-balancers

=======

EXOSCALE_TRACE=1 go run main.go compute private-network list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-private-networks
>>> Operation: list-private-networks
>>> Operation: list-private-networks
>>> Operation: list-private-networks

=======

EXOSCALE_TRACE=1 go run main.go compute security-group show sks-security-group 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-security-groups
>>> Operation: get-security-group
>>> Operation: get-security-group
>>> Operation: list-zones
>>> Operation: list-instances
>>> Operation: list-instances
>>> Operation: list-instances
>>> Operation: list-instances

=======

EXOSCALE_TRACE=1 go run main.go dbaas list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-dbaas-services
>>> Operation: list-dbaas-services
>>> Operation: list-dbaas-services
>>> Operation: list-dbaas-services

=======

EXOSCALE_TRACE=1 go run main.go compute bs list 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-block-storage-volumes
>>> Operation: list-block-storage-volumes
>>> Operation: list-block-storage-volumes
>>> Operation: list-block-storage-volumes

=======

EXOSCALE_TRACE=1 go run main.go compute bs list -z ch-gva-2 2>&1 | grep Operation:
>>> Operation: list-zones
>>> Operation: list-block-storage-volumes