Nerf `Size20` (Salvation) `RateOfFire` adjacency

[lL1l1]

Description of the proposed changes

Resolves #5781. Reduce the Size20 category's fire rate adjacency (used only by Salvation in FAF) to a maximum of 20% discount to make it reasonably worse than Mavor. It has equal dps/mass but worse splash and pays off over time worse.

- T2 Pgen reload discount: -0.0625 -> -0.025
- T3 Pgen reload discount: -0.1 -> -0.045

Old Fire rates:

Setup	Reload	DPS Boost	DPS	DPS vs Mavor	DPS vs Mavor/mass
No Adj.	3.1	100%	2,427	73%	85%
all t1	2.8	111%	2,687	81%	94%
t2 + t1	2.2	141%	3,420	103%	117%
t3	1.9	163%	3,960	119%	131%
t3 + t1	1.8	172%	4,180	125%	138%

New Fire rates (all t1 and no adj. setups unaffected):

Setup	Reload	DPS Boost	DPS	DPS vs Mavor	DPS vs Mavor/mass
t2 + t1	2.7	115%	2,787	84%	96%
t3	2.6	119%	2,894	87%	96%
t3 + t1	2.5	124%	3,010	90%	99%

Checklist

• [x] Changes are documented in the changelog for the next game version