[IMP] base: use es_419 and not es_MX as reference

And load only two languages, not three.
Faster to load and avoids ambiguity when a Mexican sees es_ES content

closes odoo/odoo#134785

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

odoo/tools/translate.py

@@ -1472,13 +1472,18 @@ def load_language(cr, lang):
     installer.lang_install()
 
 
+
 def get_po_paths(module_name: str, lang: str):
     lang_base = lang.split('_')[0]
-    langs = [lang_base, lang]  # the latter will overwrite the former
-    if lang_base == "es" and lang != "es_MX":
-        # force es_MX as fallback language for the different spanish
-        # es_MX is more actively translated and closer to many languages
-        langs = [lang_base, "es_MX", lang]
+    if lang_base == 'es' and lang != 'es_ES':
+        # force es_419 as fallback language for the spanish variations
+        if lang == 'es_419':
+            langs = ['es_419']
+        else:
+            langs = ['es_419', lang]
+    else:
+        langs = [lang_base, lang]
+
     return [
         path
         for lang_ in langs