Replaces return_file_text -> file2text (#21849)

Very ancient, decrepit proc that is somehow still used. Got rid of it in
favor of byond's proc, which has been around long enough there isn't a
version I can cite for it.

No user facing changes.

code/__HELPERS/files.dm

@@ -1,17 +1,3 @@
-//checks if a file exists and contains text
-//returns text as a string if these conditions are met
-/proc/return_file_text(filename)
-	if(fexists(filename) == 0)
-		log_asset("File not found ([filename])")
-		return
-
-	var/text = file2text(filename)
-	if(!text)
-		log_asset("File empty ([filename])")
-		return
-
-	return text
-
 /proc/get_subfolders(var/root)
 	var/list/folders = list()
 	var/list/contents = flist(root)

code/controllers/subsystems/chemistry.dm

@@ -128,7 +128,7 @@ SUBSYSTEM_DEF(chemistry)
 		return
 
 	try
-		chemconfig = json_decode(return_file_text("config/secretchem.json"))
+		chemconfig = json_decode(file2text("config/secretchem.json"))
 	catch(var/exception/e)
 		log_subsystem_chemistry("Warning: Could not load config, as secretchem.json is missing - [e]")
 		return

code/controllers/subsystems/discord.dm

@@ -68,7 +68,7 @@ SUBSYSTEM_DEF(discord)
 	PRIVATE_PROC(TRUE)
 	if(!SSdbcore.Connect())
 		log_subsystem_discord("initialize_webhooks - Unable to connect to db - Loading from File")
-		var/file = return_file_text("config/webhooks.json")
+		var/file = file2text("config/webhooks.json")
 		if (file)
 			var/jsonData = json_decode(file)
 			if(!jsonData)

code/datums/helper_datums/synthsprites.dm

@@ -31,7 +31,7 @@ paiicon is the pai icon sprite name
 		return
 
 	try
-		customsynthsprites = json_decode(return_file_text("config/customsynths.json"))
+		customsynthsprites = json_decode(file2text("config/customsynths.json"))
 	catch(var/exception/ej)
 		LOG_DEBUG("Error: Warning: Could not load custom synth config, as customsynths.json is missing - [ej]")
 		return

code/game/jobs/whitelist.dm

@@ -21,7 +21,7 @@ var/list/whitelist_jobconfig = list()
 	if(fexists("config/whitelist_jobconfig.json"))
 		LOG_DEBUG("Whitelist JobConfig: Loading from json")
 		try
-			whitelist_jobconfig = json_decode(return_file_text("config/whitelist_jobconfig.json"))
+			whitelist_jobconfig = json_decode(file2text("config/whitelist_jobconfig.json"))
 		catch(var/exception/e)
 			LOG_DEBUG("Whitelist JobConfig: Failed to load whitelist_jobconfig.json: [e]")
 

code/modules/customitems/item_spawning.dm

@@ -64,7 +64,7 @@ GLOBAL_LIST_INIT(custom_items, list())
 			var/list/loaded_items = list()
 			var/item_id = 0
 			try
-				loaded_items = json_decode(return_file_text("config/custom_items.json"))
+				loaded_items = json_decode(file2text("config/custom_items.json"))
 			catch(var/exception/e)
 				log_module_customitems("Failed to load custom_items.json: [e]")