Remove namelist.yml with hardcoded output date from conf/real-from-ideal

conf/real-from-ideal/namelists.yml

-atmosphere_namelist_ideal: |
-  &output_nml
-  /
-  &output_nml
-    steps_per_file              = 1
-    output_start                = '2020-10-01T06:00:00Z'
-    output_end                  = '2020-10-01T06:00:00Z'
-    output_filename             = "init-test-ext"
-    include_last                = .true.
-    output_interval             = 'PT3600S'
-    ml_varlist                  = 'depth_lk', 'emis_rad', 'fr_lake', 'fr_land', 'topography_c', 'soiltyp', 'sso_stdh', 'sso_theta', 'sso_gamma', 'sso_sigma'
-  /