[DOCS-12422] Update SNMP Profile Manager for GA

[git-thuerk-done]

What does this PR do? What is the motivation?

Fixes DOCS-12422

Updates the SNMP Profile Manager documentation to reflect the new UI and Agent 7.75.2+ requirements.

Prerequisites section:

• Updates minimum Agent version from 7.65 to 7.75.2
• Expands use_remote_config_profiles: true configuration to cover both SNMP Autodiscovery (datadog.yaml) and manual SNMP checks (conf.d/snmp.d/conf.yaml)
• Adds device scanning prerequisite (network_devices.default_scan.enabled: true)
• Adds note about uploading existing custom Agent profiles to the Profile Manager UI (link TBD)
• Adds EXOS 33.1.1 firmware bug warning

Troubleshooting section:

• Expands "Why would a device not be scanned?" with three additional causes: default scan disabled, infinite loop detection, and EXOS 33.1.1 firmware bug
• Renames "What if I don't have Remote Configuration enabled?" to "Remote Configuration is not enabled on collectors" and updates requirements list
• Adds GovCloud note (wrapped in site-region region="gov") to the "Why would a device not be scanned?" section

Merge instructions

Merge readiness:

• Ready for merge

Additional notes

• Flows section: No content provided yet — not included in this PR
• Custom profiles upload link: TBD from SME (Nouha Manai)
• Screenshots: May need updating for the new UI — pending screenshot availability (~end of February per SME doc)

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/aliciathuerk/DOCS-12422-snmp-profile-manager-update/network_monitoring/devices/profiles/device_profiles