[PORT] Gravity generator sound overhaul (#5349)

## About The Pull Request

Ports tgstation/tgstation#86080

<details>
<summary>Video comparisons</summary>


https://github.com/user-attachments/assets/0dc6d936-6c43-4696-9488-ced2a6f63cd2


https://github.com/user-attachments/assets/17072a5f-3254-40a1-bfaa-216b7613ece5

</details>

## Why It's Good For The Game

> Previous sound was very grating on the ears so we made a more light
one.

## Changelog

:cl: Absolucy, grungussuss, and kayozz
sound: gravity generator has a new sound
/:cl:

Co-authored-by: grungussuss <[email protected]>

code/datums/looping_sounds/machinery_sounds.dm

@@ -112,10 +112,17 @@
 	falloff_distance = 1 //Instant falloff after initial tile
 
 /datum/looping_sound/gravgen
-	mid_sounds = list('sound/machines/gravgen/gravgen_mid1.ogg' = 1, 'sound/machines/gravgen/gravgen_mid2.ogg' = 1, 'sound/machines/gravgen/gravgen_mid3.ogg' = 1, 'sound/machines/gravgen/gravgen_mid4.ogg' = 1)
-	mid_length = 1.8 SECONDS
-	extra_range = 10
-	volume = 40
+	start_sound = 'sound/machines/gravgen/grav_gen_start.ogg'
+	start_length = 1 SECONDS
+	mid_sounds = list(
+		'sound/machines/gravgen/grav_gen_mid1.ogg' = 12,
+		'sound/machines/gravgen/grav_gen_mid2.ogg' = 1,
+	)
+	mid_length = 1.1 SECONDS
+	end_sound = 'sound/machines/gravgen/grav_gen_end.ogg'
+	extra_range = 8
+	vary = TRUE
+	volume = 70
 	falloff_distance = 5
 	falloff_exponent = 20
 

sound/machines/gravgen/attribution.txt

@@ -0,0 +1,6 @@
+{
+grav_gen_start.ogg
+grav_gen_mid1.ogg
+grav_gen_mid2.ogg - + Explosion 7b by LiamG_SFX -- https://freesound.org/s/322492/ -- License: Attribution NonCommercial 4.0
+grav_gen_end.ogg
+} made by sadboysuss by editing a sound made by kayozz , license: CC-by-SA