lalmetaio: remove EventIDColumn structure

Description

Remove the EventIDColumn structure from lalmetaio, convert remaining use cases to long int.

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

The EventIDColumn structure was introduced many years ago as a hack to facilitate the use of trigger ID values for encoding coincidence and time slide information, and was replaced many years ago with the coincidence tables. Following recent cleanup of lalinspiral, there is now no code that uses the legacy EventIDColumn structure for any purpose other than to store IDs so it is possible to remove it from lalmetaio. By replacing it with a normal integer in the structures in which it appears, the swig wrappings of those structures become closer to being usable as native row object representations in the Python XML I/O library.

Review Status

Not reviewed.