tests: Fix daemon startup with non-standard paths

This was passing within the CI just because the environment adds them to
$PATH. In my personal dev environment, I'm using stuff outside of my
default $PATH. Given that CMake already checks for these executables,
let's make it work.

Change-Id: I1937c4fc294b0d1c7a9e683f3026fe178afda8a3
diff --git a/start_daemons.sh.in b/start_daemons.sh.in
index a4c428e..dc041eb 100755
--- a/start_daemons.sh.in
+++ b/start_daemons.sh.in
@@ -2,9 +2,9 @@
 shopt -s failglob
 export ASAN_OPTIONS=verify_asan_link_order=false
 export UBSAN_OPTIONS=halt_on_error=1
-sysrepod -l3
+@SYSREPOD_EXECUTABLE@ -l3
 sleep 1
-sysrepo-plugind -l3
+@SYSREPO_PLUGIND_EXECUTABLE@ -l3
 sleep 1
-netopeer2-server -U -v2 -s @NETOPEER_SOCKET_PATH@
+@NETOPEER2_EXECUTABLE@ -U -v2 -s @NETOPEER_SOCKET_PATH@
 sleep 5