Make the default behavior of copying attachments configurable when copying an issue
|Target version:||Candidate for next major release|
When copying an issue, you can select the following behaviors:
1. whether to make a relation between source and destination issues
2. whether to copy attachments
And the former has a setting to set the default behavior (#18500). However, the latter does not.
I think it should also be possible to configure the default behavior whether to copy attachments or not.