gh-148989: _remote_debugging: Remove dead code, unnecessary gc state read

[maurycy]

I don't think it warrants a NEWS. It should've been removed with 274a26c. There's no gc_state reader anymore. It should obviously reduce the memory pressure, but I didn't measure it.

• Issue: _remote_debugging: dead code, unnecessary gc state read #148989

[maurycy]

SIZEOF_GC_RUNTIME_STATE has to stay:

cpython/Modules/_remote_debugging/debug_offsets_validation.h

Line 366 in 665b7df

PY_REMOTE_DEBUG_VALIDATE_READ_SECTION(gc, SIZEOF_GC_RUNTIME_STATE);

cpython/Modules/_remote_debugging/module.c

Lines 527 to 532 in 665b7df

	uintptr_t gc_frame = 0;
	if (self->gc) {
	gc_frame = GET_MEMBER(uintptr_t, interp_state_buffer,
	self->debug_offsets.interpreter_state.gc
	+ self->debug_offsets.gc.frame);
	}

[pablogsal]

Thanks a lot for the PR @maurycy !

[pablogsal]

LGTM