MT#55283 pkg: fix missing systemd template file

> E: rtpengine-daemon: service-file-is-not-a-file lib/systemd/system/rtpengine@.service

we are getting on buster:

> dh build
>   dh_update_autotools_config
>   dh_autoreconf
>   dh_auto_configure
>   dh_auto_build

instead of (like in bullseye):

> dh build
>    dh_update_autotools_config
>    dh_autoreconf
>    debian/rules execute_before_dh_auto_configure
> make[1]: Entering directory '/build/rtpengine-11.2.0.0+0~mr11.2.0.0~bpo11.20221006010623.125'
> (cd debian && sh generate-systemd-templates.sh)
> make[1]: Leaving directory '/build/rtpengine-11.2.0.0+0~mr11.2.0.0~bpo11.20221006010623.125'
>    dh_auto_configure
>    dh_auto_build

Change-Id: If7d3bf7abf289d072793ea11162bf8ec9ef91576

pkg/deb/backports/buster

@@ -17,6 +17,7 @@ sed -i -e '/libbcg729-dev/d' ${DIST}/control
 # Update for buster debhelper
 sed -i -e 's/debhelper-compat.*/debhelper-compat (= 12),/' ${DIST}/control
 # Replace execute_* hooks with old-style overrides
+sed -i -e 's/^execute_before_dh_auto_configure:/override_dh_auto_configure:/' ${DIST}/rules
 sed -i -e 's/^execute_after_dh_installsystemd:/override_dh_installsystemd:\n\tdh_installsystemd/' ${DIST}/rules
 sed -i -e 's/^execute_before_dh_auto_install-indep:/override_dh_auto_install-indep:/' ${DIST}/rules
 sed -i -e '/^\tgzip -9 < README.md/a\\n\tdh_auto_install' ${DIST}/rules

pkg/deb/backports/stretch

@@ -20,6 +20,7 @@ sed -i -e 's/debhelper-compat.*/debhelper (>= 10),/' ${DIST}/control
 # Compat level for dkms module package
 sed -i -e '/cp debian.control/ i \	cp debian/compat debian/\$(psource)/usr/src/modules/\$(sname)/debian/' ${DIST}/rules
 # Replace execute_* hooks with old-style overrides
+sed -i -e 's/^execute_before_dh_auto_configure:/override_dh_auto_configure:/' ${DIST}/rules
 sed -i -e 's/^execute_after_dh_installsystemd:/override_dh_installsystemd:\n\tdh_installsystemd/' ${DIST}/rules
 sed -i -e 's/^execute_before_dh_auto_install-indep:/override_dh_auto_install-indep:/' ${DIST}/rules
 sed -i -e '/^\tgzip -9 < README.md/a\\n\tdh_auto_install' ${DIST}/rules