Remove remaining System Management Agent components

[lenny-goodell]

🚀 Feature Request

Relevant Package [REQUIRED]

This feature request is for System Management Agent

Description [REQUIRED]

System Management Agent no longer existings in Edgex, but the UI still contains components for it.

https://github.com/edgexfoundry/edgex-ui-go/blob/main/web/src/app/services/system-agent.service.ts
https://github.com/edgexfoundry/edgex-ui-go/blob/main/web/src/app/services/system-agent.service.spec.ts
https://github.com/edgexfoundry/edgex-ui-go/blob/76c7bda26704e13abda599293f14a45310026ab6/web/src/app/guards/health/system-agent-alive.guard.spec.ts
https://github.com/edgexfoundry/edgex-ui-go/blob/76c7bda26704e13abda599293f14a45310026ab6/web/src/app/guards/health/system-agent-alive.guard.ts

Describe the solution you'd like

These components and all references to them should be removed

Describe alternatives you've considered

Have you considered any alternative solutions or workarounds?