ci: change default packages

Since this file was taken from packages repository, it tries to compile
packages from that repository as fallback if changes are not detected.

Let's change these packages to some, which are present in this
repository, so they will be compiled as test.

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
(cherry picked from commit c9a8f2d032)

.github/workflows/multi-arch-test-build.yml

@@ -77,7 +77,7 @@ jobs:
 
           # fallback to test packages if nothing explicitly changes this is
           # should run if other mechanics in packages.git changed
-          PACKAGES="${PACKAGES:-vim attendedsysupgrade-common bmon}"
+          PACKAGES="${PACKAGES:-bird2 cjdns olsrd}"
 
           echo "Building $PACKAGES"
           echo "PACKAGES=$PACKAGES" >> $GITHUB_ENV