Install pygobject from Debian repos (#18546)

* Install pygobject from Debian repos

sonic-host-services needs pygobject installed, which is fine for amd64
and arm64, but for armhf, there's no precompiled wheel and requires
compilation.

To get around that, just install the version from Debian.
* Reduce scope of python3-gi installation to armhf only

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

files/build_templates/sonic_debian_extension.j2

@@ -242,6 +242,15 @@ sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-mark manu
 # Install systemd-python for SONiC host services
 sudo https_proxy=$https_proxy LANG=C chroot $FILESYSTEM_ROOT pip3 install systemd-python
 
+if [[ $CONFIGURED_ARCH == armhf ]]; then
+    # Install pygobject from apt repos, since it has armhf prebuilt. The version in Debian is
+    # a bit older than what is in pip.
+    #
+    # When doing the next Debian upgrade (to Trixie), consider installing this package for all
+    # architectures instead of just armhf.
+    sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y install python3-gi
+fi
+
 # Install SONiC host services package
 SONIC_HOST_SERVICES_PY3_WHEEL_NAME=$(basename {{sonic_host_services_py3_wheel_path}})
 sudo cp {{sonic_host_services_py3_wheel_path}} $FILESYSTEM_ROOT/$SONIC_HOST_SERVICES_PY3_WHEEL_NAME