apt: stop SRV lookups; give the FreeBSD VM host the fallback mirrors (#200)

Harden-Runner blocked apt's SRV lookups (_https._tcp.mirrors.edge.kernel.org,
_https._tcp.mirrors.dotsrc.org): the allow lists name the hosts, not their
SRV records. configure-apt-mirrors now sets Acquire::EnableSrvRecords false;
apt connects to the hosts directly either way.

The FreeBSD workflow's VM action apt-installs QEMU on the host, which failed
during the ubuntu.com outage (sudo exit 100) and reached packages.microsoft.com.
Run configure-apt-mirrors first and drop the image's Microsoft source, which
the job never installs from.

.github/workflows/freebsd.yml

@@ -94,6 +94,12 @@ jobs:
             x86_64|aarch64) ;;
             *) echo "::error::unsupported architecture '$ARCH' (use x86_64 or aarch64)"; exit 1 ;;
           esac
+      # The VM action apt-installs QEMU on the host: give it the mirrors outside ubuntu.com, and
+      # drop the image's Microsoft source, which this job never installs from.
+      - name: Configure apt mirrors
+        uses: storytold/craft-common-actions/actions/configure-apt-mirrors@main
+      - name: Drop the Microsoft apt source
+        run: sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list /etc/apt/sources.list.d/microsoft-prod.sources
       - name: Start the FreeBSD VM
         uses: vmactions/freebsd-vm@c46abacb49f09938ca4e1702d15d836285d694cc # v1.5.9
         with: