[SE] Exclude science packs for space lab

Speaking of [WH40k Titans mod](https://mods.factorio.com/mod/WH40k-Titans) again, I'd like to remove titans science pack from the space lab leaving it for the dedicated WH40k lab (can be built in space, btw). There is `excluded_labs` variable in `phase-4.general`, but it is not a global variable like `se_prodecural_tech_exclusions`, could you change it to be global, and/or add a more dedicated `se_exluded_science_packs`?