autopkgtest timing out waiting for testbed to start. lxc-attach: You lack access to /usr/share/debci/.local/share/lxc

Hi!

(1) The autopkgtest job for one of my packages used to work fine up to at least one month ago: https://salsa.debian.org/debian/systemtap/-/jobs/2894401

(2) Today the very same job fails: https://salsa.debian.org/debian/systemtap/-/jobs/3094004

Here's the relevant error message:

^@<VirtSubproc>: failure: timed out waiting for testbed to start: lxc-attach: ci-223-28f83855: ../src/lxc/tools/lxc_attach.c: main: 302 You lack access to /usr/share/debci/.local/share/lxc

I suspect that the upgrade of lxc from 1:4.0.11-1 to 1:5.0.1-1 could potentially be implicated, given that it happened between (1) and (2). See https://tracker.debian.org/news/1350834/accepted-lxc-1501-1-source-into-unstable/