IntegartionTests: add grhd_tov_spherical1d ref test

test/IntegrationTests/refs/grhd_tov_spherical1d/grhd_tov_spherical1d.toml

+[EquationOfState]
+eos = "polytrope"
+polytrope_k = 100.0
+polytrope_gamma = 2.0
+
+[GRHD]
+bc = "from_id"
+id = "tov"
+id_filename = "$(joinpath(ROOTDIR,\"initialdata\",\"TOV_stable.h5\"))"
+atm_factor = 1e-8
+formulation = "spherical1d"
+
+[Mesh]
+range = [ 0.0, 20.0 ]
+n = 4
+k = 124
+basis = "lgl"
+periodic = false
+
+[Output]
+variables = [ "D", "Sr", "τ" ]
+aligned_ts = "$(collect(range(2.5,10.0,step=2.5)))"
+enable1d  = true
+
+[Evolution]
+cfl = 0.4
+tend = 10.0

test/IntegrationTests/refs/testconfig.toml

@@ -80,6 +80,11 @@ reltol = 1e-6
 # runs into discontinuity
 variables  = [ "D", "Sr", "τ", "p", "ρ", "ϵ", "vr" ]
 
+[grhd_tov_spherical1d]
+# test does not use any hrsc method, so we can encounter garbage
+# but we are happy when it runs
+variables  = []
+
 # 2D tests
 
 [advection2d_sine]