deinitialize CAnnouncementManager before stopping all (network) services

partial backport of e2693c5cb5320cede4d4dd884059c4574366eef1 and b348974a3fd13d3bd6d02e308037b0862f4c8ea0.
Merge pull request #4730 from Montellese/gotham_announcement_fix

deinitialize CAnnouncementManager before stopping all (network) services