Don't track the module changes in the CHANGELOG.txt

Problem/Motivation

Do we really still need to maintain a separate file for changes, when Git does this for us (and drush rn compiles the data for release notes) ?

Drupal core stopped doing this recently. See #2647824-29: [policy and patch] Determine what should go in CHANGELOG.txt for 8.x core releases for details.

There is already more than enough work for module maintainers; let's make their lives easier.

Proposed resolution

Don't track the module changes in the CHANGELOG.txt file.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.

Release notes snippet

None.