Create a copy of the 3.0~rc1 IDF on both 'amd64' and 'i386' paths

See #11962-note_7.

The idea is to have the same IDF for 3.0 copied on both:

• https://tails.boum.org/install/v1/Tails/amd64/stable/latest.yml
• https://tails.boum.org/install/v1/Tails/i386/stable/latest.yml

This would be a way to have both:

• The current DAVE download 3.0 from the i386 IDF that it is coded to check.
• The future DAVE download 3.0 from the amd64 IDF once we did #12494 (closed).

Related issues

• Related to #12494 (closed)

Original created by @intrigeri on 12572 (Redmine)