GetServiceForServiceAccount should list all associated services

[ksubrmnn]

Please describe the Improvement and/or Feature Request

Change GetServiceForServiceAccount to so it returns a slice of MeshServices instead of a single MeshService reference. (The function itself contains a check for > 1 services and returns an error – remove)

This will removes the 1-1 mapping in OSM for Services to Service Accounts and more closely follows how ServiceAccounts map 1-1 with PodSpecs which can map to multiple services.

Scope (please mark with X where applicable)

• New Functionality [ ]
• Install [ ]
• SMI Traffic Access Policy [ ]
• SMI Traffic Specs Policy [ ]
• SMI Traffic Split Policy [ ]
• Permissive Traffic Policy [ ]
• Ingress [ ]
• Egress [ ]
• Envoy Control Plane [X]
• CLI Tool [ ]
• Metrics [ ]
• Certificate Management [ ]
• Sidecar Injection [ ]
• Logging [ ]
• Debugging [ ]
• Tests [ ]
• CI System [ ]
• Project Release [ ]

Possible use cases

This change will begin the work of programming Envoy for service accounts and not services. This work will also eventually pave the way for finding the root service of backend services with and without TrafficSplit

[ksubrmnn]

The initial PR #1553 refactored the method signature and updated references to only use the first service returned. The following lines need to be revisited in a follow up PR

Routes 245

Routes 258