Similar nags for the regular S5 are addressed in various xposed modules and custom ROMs. But the S5 Active is a niche device and there are relatively few of them out there. Meaning that anything unique to the Active model is esoteric and going to show up on the radar of a lot less people.
Your best bet is to do an exhaustive search to see if anyone has tackled this yet. In the alternative, you could try to change it yourself. It's likely a simple edit to disable the nag. But it might take a bit of effort to locate where the nag message resides.
Start with this
thread, which shows how other S5 nags have been removed. If you can't find your specific nag here, that thread would still serve as a template to locate it yourself. It would almost certainly be in the system.ui apk, so you would need to decompile that with apktool and search for strings similar to the examples there.