WarpX header: remove unused GetDistanceToEB function (#5589)

This PR removes a WarpX member function that is no longer used in WarpX.

Author: lucafedeli88

Source/WarpX.H

@@ -162,12 +162,7 @@ public:
     HybridPICModel& GetHybridPICModel () { return *m_hybrid_pic_model; }
     [[nodiscard]] HybridPICModel * get_pointer_HybridPICModel () const { return m_hybrid_pic_model.get(); }
     MultiDiagnostics& GetMultiDiags () {return *multi_diags;}
-#ifdef AMREX_USE_EB
-    ablastr::fields::MultiLevelScalarField GetDistanceToEB () {
-        using warpx::fields::FieldType;
-        return m_fields.get_mr_levels(FieldType::distance_to_eb, finestLevel());
-    }
-#endif
+
     ParticleBoundaryBuffer& GetParticleBoundaryBuffer () { return *m_particle_boundary_buffer; }
     amrex::Vector<std::array< std::unique_ptr<amrex::iMultiFab>,3 > >& GetEBUpdateEFlag() { return m_eb_update_E; }