VOLDEV-42 - Remove fixed width on article comments textarea when editing replies

@Grunny @michalroszka 
Also, see question about other fixed width textarea in same file: https://wikia-inc.atlassian.net/browse/VOLDEV-42?focusedCommentId=85944&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-85944