refactor: Remove Meteor.runAsUser part 1 (#28909)

apps/meteor/app/api/server/v1/chat.ts

apps/meteor/app/api/server/v1/integrations.ts

apps/meteor/app/api/server/v1/users.ts

apps/meteor/app/authentication/server/startup/index.js

apps/meteor/app/importer-pending-avatars/server/importer.js

apps/meteor/app/integrations/server/api/api.js

...ions/server/methods/incoming/deleteIncomingIntegration.ts

...ions/server/methods/outgoing/deleteOutgoingIntegration.ts

...eor/app/lib/server/functions/checkUsernameAvailability.ts

apps/meteor/app/lib/server/functions/deleteMessage.ts

apps/meteor/app/lib/server/functions/index.ts

apps/meteor/app/lib/server/functions/joinDefaultChannels.ts

apps/meteor/app/lib/server/functions/setUserAvatar.ts

apps/meteor/app/lib/server/functions/setUsername.ts

...eteor/app/lib/server/methods/checkUsernameAvailability.ts

apps/meteor/app/lib/server/methods/deleteMessage.ts

apps/meteor/app/lib/server/methods/setUsername.ts

apps/meteor/server/methods/deleteFileMessage.ts

apps/meteor/server/methods/saveUserPreferences.ts

apps/meteor/server/methods/setAvatarFromService.ts