Improves Readability/Documentation of SSTicker.force_ending (#71329)

## About The Pull Request

Hey there,

force_ending was a boolean (with inconsistent usage, flip-flopping
between using TRUE/FALSE and 1/0 variables), so let's just change it all
over to the macros and call it a good day.

I also updated documentation of the variables in that "code block" in
SSTicker while in the area because changing just one line made it look
ugly. Some of the documentation was no longer current to it's... current
use in code, so I updated those as well.
## Why It's Good For The Game

Pure code improvement, DMdocs are swell, and readability is kino.
## Changelog
Nothing here should affect players.

code/modules/admin/verbs/server.dm

@@ -77,7 +77,7 @@
 	if(confirm == "Cancel")
 		return
 	if(confirm == "Yes")
-		SSticker.force_ending = 1
+		SSticker.force_ending = TRUE
 		SSblackbox.record_feedback("tally", "admin_verb", 1, "End Round") //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
 
 /datum/admins/proc/toggleooc()