ci(apt): pin Azure mirror as primary via priority: annotations

`apt-transport-mirror` treats unannotated peer URLs in a mirrorlist as
equal, and spreads each `apt-get update` request across them for load
balancing. That combined with `mirror+file://` in bf848fa means one
`InRelease` can come from azure while the matching `Packages.gz` comes
from archive.ubuntu.com (or vice versa), and when the two hosts are
mid-sync apt fails with:

  File has unexpected size (4263777 != 4263737). Mirror sync in progress?

Observed on an earlier PR run at step:15 line 881 — archive served an
`InRelease` that disagreed with the `Packages.gz` its mirror had just
rotated. `Acquire::Retries` doesn't help here because the bad file is
consistently returned until the mirror finishes its push.

Annotate the mirrorlist with `priority:` (lower = preferred) so every
request goes to azure first and archive is touched only when azure
fails. This eliminates the cross-host version-skew race entirely;
the only remaining case is a mid-push on azure alone, which is rare
and typically covered by `Acquire::Retries`.

Secondary benefit: on GHA runners (which live inside Azure's network)
azure.archive.ubuntu.com is an order of magnitude faster than the
public archive.ubuntu.com, so pinning azure as primary is also a
throughput win — "load balancing" over an unevenly fast pair was a
pessimization, not a speedup.

Signed-off-by: Mete Fatih Cırıt <mfc@autoware.org>

Author: xmfcx

.github/workflows/setup-universe.yaml

@@ -46,7 +46,7 @@ jobs:
           echo 'Acquire::Retries "5";' > /etc/apt/apt.conf.d/99-retries
           echo 'Acquire::http::Timeout "30";' >> /etc/apt/apt.conf.d/99-retries
           echo 'Acquire::https::Timeout "30";' >> /etc/apt/apt.conf.d/99-retries
-          printf 'http://azure.archive.ubuntu.com/ubuntu\nhttp://archive.ubuntu.com/ubuntu\n' > /etc/apt/ubuntu-mirrors.list
+          printf 'http://azure.archive.ubuntu.com/ubuntu\tpriority:1\nhttp://archive.ubuntu.com/ubuntu\tpriority:2\n' > /etc/apt/ubuntu-mirrors.list
           for f in /etc/apt/sources.list /etc/apt/sources.list.d/ubuntu.sources; do
             if [ -f "$f" ]; then
               sed -E -i 's|http://archive\.ubuntu\.com/ubuntu/?|mirror+file:///etc/apt/ubuntu-mirrors.list|g' "$f"

docker-new/base.Dockerfile

@@ -14,7 +14,7 @@ RUN rm -f /etc/apt/apt.conf.d/docker-clean && \
     echo 'Acquire::Retries "5";' > /etc/apt/apt.conf.d/99-retries && \
     echo 'Acquire::http::Timeout "30";' >> /etc/apt/apt.conf.d/99-retries && \
     echo 'Acquire::https::Timeout "30";' >> /etc/apt/apt.conf.d/99-retries && \
-    printf 'http://azure.archive.ubuntu.com/ubuntu\nhttp://archive.ubuntu.com/ubuntu\n' > /etc/apt/ubuntu-mirrors.list && \
+    printf 'http://azure.archive.ubuntu.com/ubuntu\tpriority:1\nhttp://archive.ubuntu.com/ubuntu\tpriority:2\n' > /etc/apt/ubuntu-mirrors.list && \
     for f in /etc/apt/sources.list /etc/apt/sources.list.d/ubuntu.sources; do \
       if [ -f "$f" ]; then \
         sed -E -i 's|http://archive\.ubuntu\.com/ubuntu/?|mirror+file:///etc/apt/ubuntu-mirrors.list|g' "$f"; \