Remove the currencies field from stores.

The new product architecture allows a product to belong to multiple stores,
making it unfeasible to limit available currencies per store.

modules/store/config/install/core.entity_form_display.commerce_store.online.default.yml

-langcode: en
-status: true
-dependencies:
-  config:
-    - commerce_store.commerce_store_type.online
-id: commerce_store.online.default
-targetEntityType: commerce_store
-bundle: online
-mode: default
-content:
-  currencies:
-    type: options_buttons
-    weight: 20
-    settings: {  }
-    third_party_settings: {  }
-hidden: {  }

modules/store/config/install/field.field.commerce_store.online.currencies.yml

-langcode: en
-status: true
-dependencies:
-  config:
-    - commerce_store.commerce_store_type.online
-    - field.storage.commerce_store.currencies
-  module:
-    - entity_reference
-id: commerce_store.online.currencies
-field_name: currencies
-entity_type: commerce_store
-bundle: online
-label: Currencies
-description: 'All currencies allowed for the store.'
-required: true
-translatable: false
-default_value: {  }
-default_value_callback: ''
-settings:
-  handler: 'default:commerce_currency'
-  handler_settings:
-    sort:
-      field: _none
-field_type: entity_reference

modules/store/config/install/field.storage.commerce_store.currencies.yml

-langcode: en
-status: true
-dependencies:
-  module:
-    - commerce_store
-    - entity_reference
-id: commerce_store.currencies
-field_name: currencies
-entity_type: commerce_store
-type: entity_reference
-settings:
-  target_type: commerce_currency
-module: entity_reference
-locked: true
-cardinality: -1
-translatable: false
-indexes: {  }
-persist_with_no_fields: false