Merge pull request #6085 from oswaldoacauan/fix-missing-stuff-on-meeting-removal

.../api/group-chat-msg/server/modifiers/clearGroupChatMsg.js

...l5/imports/api/meetings/server/modifiers/removeMeeting.js

...esentation-pods/server/modifiers/clearPresentationPods.js

...esentation-pods/server/modifiers/removePresentationPod.js

...ad-token/server/modifiers/clearPresentationUploadToken.js

.../api/presentations/server/modifiers/clearPresentations.js