Revert "[MIRROR] Replace all secondary flags with bitflags stored in the flags_2 var" (#2457)

ok you know what yeah i think i'll properly mirror https://github.com/Citadel-Station-13/Citadel-Station-13/pull/2411

code/game/mecha/mecha.dm

@@ -23,7 +23,7 @@
 	layer = BELOW_MOB_LAYER//icon draw layer
 	infra_luminosity = 15 //byond implementation is bugged.
 	force = 5
-	flags_1 = HEAR_1
+	flags = HEAR
 	var/can_move = 1
 	var/mob/living/carbon/occupant = null
 	var/step_in = 10 //make a step in step_in/10 sec.
@@ -112,7 +112,7 @@
 	var/nextsmash = 0
 	var/smashcooldown = 3	//deciseconds
 
-	var/occupant_sight_flags = 0 //sight flags_1 to give to the occupant (e.g. mech mining scanner gives meson-like vision)
+	var/occupant_sight_flags = 0 //sight flags to give to the occupant (e.g. mech mining scanner gives meson-like vision)
 
 	hud_possible = list (DIAG_STAT_HUD, DIAG_BATT_HUD, DIAG_MECH_HUD, DIAG_TRACK_HUD)
 

code/game/mecha/mecha_parts.dm

@@ -7,7 +7,7 @@
 	icon = 'icons/mecha/mech_construct.dmi'
 	icon_state = "blank"
 	w_class = WEIGHT_CLASS_GIGANTIC
-	flags_1 = CONDUCT_1
+	flags = CONDUCT
 	origin_tech = "programming=2;materials=2;engineering=2"
 
 /obj/item/mecha_parts/chassis
@@ -313,7 +313,7 @@
 	item_state = "electronic"
 	lefthand_file = 'icons/mob/inhands/misc/devices_lefthand.dmi'
 	righthand_file = 'icons/mob/inhands/misc/devices_righthand.dmi'
-	flags_1 = CONDUCT_1
+	flags = CONDUCT
 	force = 5
 	w_class = WEIGHT_CLASS_SMALL
 	throwforce = 0