fix: Remove csv_import event types from 2.14 version

Only keep in 2.15 (latest) since this repo has no Unstable version.
Per API versioning policy, avoid shipping to previous versions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: thibault-intercom

descriptions/2.14/api.intercom.io.yaml

@@ -14233,8 +14233,6 @@ components:
           - conversation_topic_change
           - conversation_topic_creation
           - conversation_topic_deletion
-          - csv_import_completion
-          - csv_import_creation
           - custom_authentication_token_creation
           - help_center_settings_change
           - inbound_conversations_change