Revert "Add templatetags.to_canonical_url to mark_function_args_lack_nltext"
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 bdc5218102affefd89d99c57737440c3c17dc88a.

Test plan: see bdc52181

Auditors: csilvers

csilvers/i18nize_templates,Khan/i18nize_templates