Drop unit level lines the game never reads

[burnhamrobertp]

Nine lines the game never reads, all weapondef tags or dead spellings sitting at unit level.

The four antinuke ships set energypershot at unit level as well as inside their antinuke weapondef, both at 7500 - the engine's unitdef has no such field and the weapon already comes out with energyCost 7500, so the stockpile cost these look like they are setting is handled a level down either way. scavempspawner does the same with craterboost, cratermult and impulsefactor, and there the unit level impulsefactor reads 0 while the weapon that actually applies says 0.123. critter_gull has collide = false and collision = false on consecutive lines, the second being the dead spelling.

legfloat is a slightly different case. Its description = "Floating Tank" is a real tag, but it only feeds the engine tooltip, and the interface goes through units.json, so what players see is "Heavy Convertible Tank/Boat" and always has. Removing the line leaves that as the only description, which is the one we want anyway - "floating tank" suggests something slower in the water than this thing is.

No behaviour change, nothing displayed or simulated comes from any of these.

Found by the def invariant checks in #8630.

[github-actions]

Integration Test Results

15 tests  ±0   7 ✅ ±0   4s ⏱️ ±0s
 1 suites ±0   8 💤 ±0 
 1 files   ±0   0 ❌ ±0 

Results for commit d1136a9. ± Comparison against base commit e03f8af.

♻️ This comment has been updated with latest results.