move all sensor daemons to libexec

Per the organization anti-pattern, executables are expected to be
installed into libexec instead of bin[1].  Update service files and
meson to install there.

[1]: https://github.com/openbmc/docs/blob/master/anti-patterns.md#incorrect-placement-of-executables-in-sbin-usrsbin-or-bin-usrbin

Change-Id: I1eb4003e94b83b09829d63346c2e16a3ff02a3e9
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/src/leakdetector/meson.build b/src/leakdetector/meson.build
index aa953e4..83225b8 100644
--- a/src/leakdetector/meson.build
+++ b/src/leakdetector/meson.build
@@ -17,5 +17,5 @@
     ],
     include_directories: src_inc,
     install: true,
-    install_dir: get_option('libexecdir') / 'dbus-sensors',
+    install_dir: '/usr/libexec/dbus-sensors',
 )