Bugfix in TDDFPT: stop_lr is used by turbo_lanczos, turbo_davidson,

and turbo_eels. turbo_eels performs NSCF calculations, this is
why we intoduced calls to mp_start_diag, set_mpi_comm_4_solvers,
and unset_mpi_comm_4_solvers. Instead, turbo_lanczos, turbo_davidson
do not perform NSCF, so these calls are not needed. Since the
call to unset_mpi_comm_4_solvers is inside of stop_lr, this
was breaking turbo_lanczos and turbo_davidson.
3 jobs for fix_tddfpt in 7 minutes and 26 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #168773835
docker
build:cp

00:04:35

passed #168773836
docker
build:ph

00:07:26

passed #168773832
docker
build:pw

00:05:42