Make the verification cancelled dialog say OK instead of Cancel

Fixes https://github.com/vector-im/riot-web/issues/9306

Includes unexpected cleanup of i18n

src/components/views/verification/VerificationCancelled.js

@@ -31,7 +31,7 @@ export default class VerificationCancelled extends React.Component {
                     "The other party cancelled the verification.",
                 )}</p>
                 <DialogButtons
-                    primaryButton={_t('Cancel')}
+                    primaryButton={_t('OK')}
                     hasCancel={false}
                     onPrimaryButtonClick={this.props.onDone}
                 />