ttcn3-bts-test-latest: use osmocom-bb-host-master

Do not try to run a osmocom-bb-host-latest docker image, which does not
exist as we are not tagging release versions for osmocom-bb (yet).

This was done right in the docker_images_require call at the top
already (which is why it did not try to build such a "-latest" image),
but then the script tried to use the "-latest" images anyway (instead
of hardcoding "-master").

Related: OS#3767
Change-Id: Ib743f09c71d93bf4c4ad947ef62b37de6b2d7ecc

ttcn3-bts-test/jenkins.sh

@@ -50,7 +50,7 @@ docker run	--rm \
 		--network $NET_NAME --ip 172.18.9.21 \
 		-v $VOL_BASE_DIR/fake_trx:/data \
 		--name ${BUILD_TAG}-fake_trx -d \
-		$REPO_USER/osmocom-bb-host-$IMAGE_SUFFIX \
+		$REPO_USER/osmocom-bb-host-master \
 		/tmp/osmocom-bb/src/target/trx_toolkit/fake_trx.py \
 			--log-file-name /data/fake_trx.log \
 			--log-file-level DEBUG \
@@ -62,7 +62,7 @@ docker run	--rm \
 		--network $NET_NAME --ip 172.18.9.22 \
 		-v $VOL_BASE_DIR/unix:/data/unix \
 		--name ${BUILD_TAG}-trxcon -d \
-		$REPO_USER/osmocom-bb-host-$IMAGE_SUFFIX \
+		$REPO_USER/osmocom-bb-host-master \
 		/usr/local/bin/trxcon -i 172.18.9.21 -s /data/unix/osmocom_l2