tests: Depend on daemon for integration test

The carefree developer might try running meson test
before meson compile, leaving them with a failing integration test:

Start of lfb-integration tests
dbus-daemon[326641]: [session uid=1000 pid=326641 pidfd=8] Activating service name='org.sigxcpu.Feedback' requested by ':1.0' (uid=1000 pid=326640 comm="$(pwd)/_build/tests/te")
+ exec $(pwd)/_build/src/feedbackd
$(pwd)/_build/run: 18: exec: $(pwd)/_build/src/feedbackd: not found

Signed-off-by: Evangelos Ribeiro Tzaras <devrtz@fortysixandtwo.eu>

src/meson.build

@@ -53,7 +53,7 @@ if get_option('daemon')
     dependencies: fbd_deps,
   )
 
-  executable(
+  fbd_exe = executable(
     'feedbackd',
     sources: ['fbd.c', generated_dbus_sources[1]],
     include_directories: fbd_inc,