Remove unexisting CMake target
Remove unexisting CMake target

The `sql_schemas_target` is not generated anymore,
but was still present in the OUTPUT section of
`add_custom_command` rule. That was causing
`make` to rebuild the target every time.

Signed-off-by: Eugene Smirnov <a16d8468c5d1db13e92eb74ab4de95e1b7a8acf9@here.com>

advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr