Revert changes to default language config

A recent issue brought up a good point about how the latest changes to
setting default language to english break functionality for bilingual
users. The change was likely not the best solution for users who were
being affected by IP geolocation on their instances -- the right
solution for that would be to configure the interface/search language to
their preference instead.

app/request.py

@@ -20,9 +20,6 @@ DESKTOP_UA = '{}/5.0 (X11; {} x86_64; rv:75.0) Gecko/20100101 {}/75.0'
 # Valid query params
 VALID_PARAMS = ['tbs', 'tbm', 'start', 'near', 'source', 'nfpr']
 
-# Fallback language if none have been configured
-DEFAULT_LANG = 'lang_en'
-
 
 class TorError(Exception):
     """Exception raised for errors in Tor requests.
@@ -112,7 +109,7 @@ def gen_query(query, args, config, near_city=None) -> str:
         )) if lang else ''
     else:
         param_dict['lr'] = '&lr=' + (
-            config.lang_search if config.lang_search else DEFAULT_LANG
+            config.lang_search if config.lang_search else ''
         )
 
     # 'nfpr' defines the exclusion of results from an auto-corrected query
@@ -122,7 +119,7 @@ def gen_query(query, args, config, near_city=None) -> str:
     param_dict['cr'] = ('&cr=' + config.ctry) if config.ctry else ''
     param_dict['hl'] = '&hl=' + (
         config.lang_interface.replace('lang_', '')
-        if config.lang_interface else DEFAULT_LANG.replace('lang_', '')
+        if config.lang_interface else ''
     )
     param_dict['safe'] = '&safe=' + ('active' if config.safe else 'off')
 
@@ -158,7 +155,7 @@ class Request:
         send_tor_signal(Signal.HEARTBEAT)
 
         self.language = (
-            config.lang_search if config.lang_search else DEFAULT_LANG
+            config.lang_search if config.lang_search else ''
         )
         self.mobile = 'Android' in normal_ua or 'iPhone' in normal_ua
         self.modified_user_agent = gen_user_agent(self.mobile)