[windows] move service startup to beginning of run function

[leehinman]

Currently elastic-agent does several things before it communicates with the Windows Service Manager and registers itself and reports as running.

elastic-agent/internal/pkg/agent/cmd/run.go

Line 143 in 81e112d

go service.ProcessWindowsControlEvents(stopBeat)

This can cause problems because the service manager has a very short timeout between when it starts a process and expects that process to communicate that it is in StartPending state. For Windows we need to move this as close as possible to the start of the run function.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)