Add missing binary install in meson build

The service was failing with the exit code 203/EXEC since the
executable was not installed under /usr/sbin. The unit file existed,
but the binary was missing at the expected path.

Add install statements to the executable block to place the binary
under /usr/sbin. By default, meson would otherwise install it under
/usr/bin.

Tested:
callback-manager.service is active with binary installed.

Change-Id: I442ecd35d1e2cca6c6f6d73e391f675470093e5b
Signed-off-by: Swaroop Aradhya N M <swaroopx.aradhya.n.m@intel.com>
1 file changed