Revert "Add templatetags.to_canonical_url to mark_function_args_lack_…

…nltext"

Apparently we can in fact do this in `i18n_lint.py`, which is better for
KA-specific things.  So we'll do that instead.

This reverts commit bdc5218.

Test plan: see bdc5218

Auditors: csilvers

i18nize_templates/__init__.py

@@ -331,7 +331,6 @@ def _init():
         'youtube.player_embed',
         'log.date.strftime',
         'emails.tracking_image_url',
-        'templatetags.to_canonical_url'
         )
 
     mark_function_param_lacks_nltext(