chore: remove year from idea copyright template

[jdrueckert]

Based on our discussion on Discord and the resulting decision to remove the year from our in-file copyright notices (see link).

Summary:

There's unclarity on whether the copyright year refers to the date of file creation, last change, or the current year.
Date of creation is hard to track and loses meaning in the light of code changes, moves, or copies.
Current year introduces maintenance overhead, especially for small maintainer groups such as ours.
Many organizations started removing the year from the in-file copyright notices.

Apache License requires us to include a LICENSE and a NOTICE file and to maintain file-level copyright notices.
It doesn't object to changing file-level copyright notices, for instance, removing the year.

[BenjaminAmos]

The licence does not appear to mandate a precise form of copyright notice, so this should be acceptable.

[jdrueckert]

The failing integration test is a known sporadic that is unrelated to the changes in this PR.
Merging despite failing checks.