[NO GBP] Partially reverts a change to *Rusted Ritual* (#85986)

## About The Pull Request

Partially reverts a change i made to Rust walkers summoning ritual by
having it require Iron(slightly more than it once did) instead of
titanium.

Link to my previous pr:
https://github.com/tgstation/tgstation/pull/83765

## Why It's Good For The Game

Couple of months ago i made rust walkers more expensive to summon as the
result of how punishing the vomiting chain stun inflicted by rust was,
Initially i thought rust walkers were the problem, as they allowed the
heretic to spread rust much quicker than you'd be able to do on their
own.

That was the wrong way to tackle the problem though, As from what i've
seen barely anybody bothers summons these guys after i changed the
recipe, and it didn't make Rust heretic any less oppressive.

What needed addressing is how oppressive the vomiting was, which
admittedly it did change.

The vomit is now a knockdown instead of a hard stun and cannot costantly
chain proc thanks to this PR.

https://github.com/tgstation/tgstation/pull/85944

We do want Heretics to use summons, it brings other players into the fun
and makes the round chaotic in a fun way.

That's why i'm partially reverting the nerf, it still requires more iron
than it once did, 10 sheets instead of 5.

Admittedly titanium as a reagent was a bit stupid considering it cannot
even rust IRL, oh well....

## Changelog

🆑

balance: Rusted Ritual now requries 10 sheets of Iron instead of
Titanium.
/🆑

code/modules/antagonists/heretic/knowledge/side_rust_cosmos.dm

@@ -86,7 +86,7 @@
 
 /datum/heretic_knowledge/summon/rusty
 	name = "Rusted Ritual"
-	desc = "Allows you to transmute a pool of vomit, some cable coil, and 5 sheets of titanium into a Rust Walker. \
+	desc = "Allows you to transmute a pool of vomit, some cable coil, and 10 sheets of iron into a Rust Walker. \
 		Rust Walkers excel at spreading rust and are moderately strong in combat."
 	gain_text = "I combined my knowledge of creation with my desire for corruption. The Marshal knew my name, and the Rusted Hills echoed out."
 	next_knowledge = list(
@@ -95,7 +95,7 @@
 	)
 	required_atoms = list(
 		/obj/effect/decal/cleanable/vomit = 1,
-		/obj/item/stack/sheet/mineral/titanium = 5,
+		/obj/item/stack/sheet/iron = 10,
 		/obj/item/stack/cable_coil = 15,
 	)
 	mob_to_summon = /mob/living/basic/heretic_summon/rust_walker