fix: resolve agent hang on shutdown when stop signal sent during active scan

[leoparente]

This pull request refactors the OTLP shutdown logic in the orbAgent and improves the logging behavior in the OTLP bridge server. The main focus is on simplifying the shutdown process by removing unnecessary context passing and ensuring consistent logging.

OTLP shutdown refactoring:

• Changed the shutdownOTLP method in agent/agent.go to no longer require a context parameter, instead always using a background context with timeout. This simplifies shutdown calls and avoids potential nil context issues.
• Updated all calls to shutdownOTLP in agent/agent.go to remove the context argument, ensuring consistency with the new method signature. [1] [2]

Logging improvements:

• Moved the "OTLP bridge server started" log statement in agent/otlpbridge/server.go outside the gRPC serving goroutine, so it always logs when the server starts, regardless of serve errors.

[github-actions]

Go test coverage

STATUS	ELAPSED	PACKAGE	COVER	PASS	FAIL	SKIP
🟢 PASS	1.02s	github.com/netboxlabs/orb-agent/agent	45.2%	6	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend	76.4%	48	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/devicediscovery	66.5%	4	0	0
🟢 PASS	0.05s	github.com/netboxlabs/orb-agent/agent/backend/mocks	0.0%	0	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/networkdiscovery	58.3%	4	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/opentelemetryinfinity	45.2%	2	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/pktvisor	66.5%	2	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/snmpdiscovery	58.3%	4	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/backend/worker	67.8%	7	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/config	100.0%	6	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/configmgr	49.5%	33	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/configmgr/fleet	64.4%	147	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/otlpbridge	50.2%	10	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/policies	98.9%	18	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/policymgr	71.6%	11	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/redact	81.6%	84	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/secretsmgr	47.1%	65	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/telemetry	81.7%	19	0	0
🟢 PASS	(cached)	github.com/netboxlabs/orb-agent/agent/version	100.0%	1	0	0

Total coverage: 59.6%

[jajeffries]

LGTM