Remove routes for enabling and disabling a currency

Problem/Motivation

There are two routes that are used for enabling and disabling a currency: entity.currency.enable and entity.currency.disable.

These routes were used in Drupal 7 and earlier and were ported as part of the Drupal 8 update, but they are not actually used. They were also implicated in a security vulnerability (ref. SA-CONTRIB-2025-110 → ).

Let's remove them.

API changes

While the two routes are not used by the module itself they might be used by existing projects, so this is a B/C break. Let's do this for the next major 4.x release.