[NL] NLS; Release non-equilibrium rhs if used.

This avoids a warning at the end for unused vectors.

NumLib/ODESolver/NonlinearSolver.cpp

@@ -448,4 +448,21 @@ createNonlinearSolver(GlobalLinearSolver& linear_solver,
 #endif
     OGS_FATAL("Unsupported nonlinear solver type '{:s}'.", type.c_str());
 }
+
+NonlinearSolver<NonlinearSolverTag::Picard>::~NonlinearSolver()
+{
+    if (_r_neq != nullptr)
+    {
+        NumLib::GlobalVectorProvider::provider.releaseVector(*_r_neq);
+    }
+}
+
+NonlinearSolver<NonlinearSolverTag::Newton>::~NonlinearSolver()
+{
+    if (_r_neq != nullptr)
+    {
+        NumLib::GlobalVectorProvider::provider.releaseVector(*_r_neq);
+    }
+}
+
 }  // namespace NumLib

NumLib/ODESolver/NonlinearSolver.h

@@ -94,6 +94,8 @@ public:
     {
     }
 
+    ~NonlinearSolver();
+
     //! Set the nonlinear equation system that will be solved.
     //! TODO doc
     void setEquationSystem(System& eq, ConvergenceCriterion& conv_crit)
@@ -172,6 +174,8 @@ public:
     {
     }
 
+    ~NonlinearSolver();
+
     //! Set the nonlinear equation system that will be solved.
     //! TODO doc
     void setEquationSystem(System& eq, ConvergenceCriterion& conv_crit)