build_container.sh: use eatmydata for apt operations

[epilys]

Summary of the PR

eatmydata disables fsync and similar operations to speed up data operations for ephemeral tasks (like building a container image).

See: https://packages.debian.org/bookworm/eatmydata

Requirements

Before submitting your PR, please make sure you addressed the following requirements:

• [x] All commits in this PR are signed (with git commit -s), and the commit message has max 60 characters for the summary and max 75 characters for each description line.
• [x] All added/changed functionality has a corresponding unit/integration test.
• [x] All added/changed public-facing functionality has entries in the "Upcoming Release" section of CHANGELOG.md (if no such section exists, please create one).
• [x] Any newly added unsafe code is properly documented.

[epilys]

Looks like this does not reduce build time significantly, closing.