Run build_linux in docker using an older glibc

[t3chguy]

Requires #598
Fixes element-hq/element-web#24981

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Here's what your changelog entry will look like:

🐛 Bug Fixes

• Run build_linux in docker using an older glibc (#599). Fixes Segfault on Debian 10: Seshat unexpected error: Error: /lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.29' not found element-web#24981.

[andybalaam]

Looks good. I was worried about how we keep this image up-to-date but I see you're on that with #598 . Nice!

[RiotRobot]

The backport to staging failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-staging staging
# Navigate to the new working tree
cd .worktrees/backport-staging
# Create a new branch
git switch --create backport-599-to-staging
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 718d5a803770d6695d651523a61917640907e674
# Push it to GitHub
git push --set-upstream origin backport-599-to-staging
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-staging

Then, create a pull request where the base branch is staging and the compare/head branch is backport-599-to-staging.