glsl: Delete lower_texture_projection

This is only used by i965 and we've been getting it through
nir_lower_tex since forever.  Get rid of the GLSL IR pass.

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11827>

src/intel/compiler/brw_vec4_nir.cpp

@@ -2078,7 +2078,7 @@ vec4_visitor::nir_emit_texture(nir_tex_instr *instr)
       }
 
       case nir_tex_src_projector:
-         unreachable("Should be lowered by do_lower_texture_projection");
+         unreachable("Should be lowered by nir_lower_tex");
 
       case nir_tex_src_bias:
          unreachable("LOD bias is not valid for vertex shaders.\n");