test-solver: Remove BoutInitialise and BoutFinalise

BoutFinalise throws an exception when ADIOS is enabled but
BoutInitialise is not called.

BoutInitialise throws an exception if the "data" directory
doesn't exist.

For this test neither BoutInitialise nor BoutFinalise are needed,
so removed.

tests/integrated/test-solver/test_solver.cxx

@@ -25,7 +25,6 @@ class TestSolver : public PhysicsModel {
 };
 
 int main(int argc, char** argv) {
-  BoutInitialise(argc, argv);
 
   // The expected answer to the integral of \f$\int_0^{\pi/2}\sin^2(t)\f$
   constexpr BoutReal expected = PI / 4.;
@@ -147,8 +146,6 @@ int main(int argc, char** argv) {
     }
   }
 
-  BoutFinalise(false);
-
   if (!errors.empty()) {
     output_test << "\n => Some failed tests\n\n";
     for (auto& error : errors) {