delete unused tailsitter_recovery library (#9103)

src/modules/mc_att_control/CMakeLists.txt

src/modules/mc_att_control/mc_att_control_main.cpp

...modules/mc_att_control/tailsitter_recovery/CMakeLists.txt

...c_att_control/tailsitter_recovery/tailsitter_recovery.cpp

.../mc_att_control/tailsitter_recovery/tailsitter_recovery.h

src/modules/mc_pos_control/mc_pos_control_main.cpp

src/modules/vtol_att_control/vtol_att_control_params.c