Fix: Memory leak in reservoir test

The test `RigReservoirTest_BasicTest10k_NativeECL_Test` was allocating
an `ecl_grid_type` object but was not freeing it, leading to a memory
leak.

This commit fixes the issue by calling `ecl_grid_free` at the end of
the test.

ApplicationLibCode/UnitTests/RifReaderEclipseOutput-Test.cpp

@@ -160,6 +160,7 @@ TEST( RigReservoirTest, BasicTest10k_NativeECL )
 #ifdef _MSC_VER
 #pragma warning( pop )
 #endif
+    ecl_grid_free( grid );
 }
 
 TEST( RigReservoirTest, Test10k_ReadThenWriteToECL )