Hopefully fixes hijack bug (#5261)

# About the pull request
Will hopefully stop hijack ending the round prematurely.
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# Explain why it's good for the game
# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

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# Changelog
:cl:
fix: Hijack should no longer end the round immediately.
/:cl:

code/__DEFINES/dcs/signals/signals_global.dm

@@ -70,3 +70,4 @@
 #define COMSIG_GLOB_GENERATOR_SET_OVERLOADING "!generator_set_overloading"
 
 #define COMSIG_GLOB_HIJACK_IMPACTED "!hijack_impacted"
+#define COMSIG_GLOB_HIJACK_LANDED "!hijack_landed"

code/controllers/subsystem/ticker.dm

@@ -478,7 +478,6 @@ SUBSYSTEM_DEF(ticker)
 
 	winset(C, null, "mainwindow.icon=[SSticker.mode.taskbar_icon]")
 
-
 /datum/controller/subsystem/ticker/proc/hijack_ocurred()
 	if(mode)
 		mode.is_in_endgame = TRUE

code/modules/shuttle/dropship_hijack.dm

@@ -51,6 +51,7 @@
 	// Break the ultra-reinforced windows.
 	// Break the briefing windows.
 	SEND_GLOBAL_SIGNAL(COMSIG_GLOB_HIJACK_IMPACTED)
+	RegisterSignal(SSdcs, COMSIG_GLOB_HIJACK_LANDED, PROC_REF(finish_landing))
 
 	// Sleep while the explosions do their job
 	var/explosion_alive = TRUE
@@ -62,6 +63,7 @@
 				break
 		sleep(10)
 
+/datum/dropship_hijack/almayer/proc/finish_landing()
 	SShijack.announce_status_on_crash()
 	SSticker.hijack_ocurred()
 

code/modules/shuttle/shuttles/dropship.dm

@@ -284,6 +284,7 @@
 			affected_mob.apply_effect(3, WEAKEN)
 
 	SEND_GLOBAL_SIGNAL(COMSIG_GLOB_GROUNDSIDE_FORSAKEN_HANDLING)
+	SEND_GLOBAL_SIGNAL(COMSIG_GLOB_HIJACK_LANDED)
 
 /datum/map_template/shuttle/alamo
 	name = "Alamo"