[9.18] Make Debian 12 "bookworm" the base image

Just replace "bullseye" with "bookworm" and reintroduce Debian 11 "bullseye" later.

(cherry picked from commit 2d18c57c)

Backport of MR !8075 (merged)

Closes #3893 (closed)

Edited by Michal Nowak

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