You can use the forward compatibility flag when creating the OpenGL context. With GLFW, this means:
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
This will be detected by LWJGL and it will not load function pointers for any deprecated OpenGL function. This will work with either Core or Compatibility profile contexts, which is important, because using the Core profile often means additional driver overhead. Note this will only work with functions, LWJGL cannot do anything about deprecated constants. You can use a Core profile context to be absolutely sure:
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // requires OpenGL 3.2 or later
For more information, see
Core and Compatibility in Contexts.
On legacy functionality, modern GPUs indeed have no hardware dedicated to obsolete OpenGL features. They're emulated with shaders managed by the driver.