Remove aria-pressed where it's redundant (#19912)

This commit removes aria-pressed attribute from all elements which
contents or other descriptive attributes change in active state,
effectively replacing the meaning of the button, in which case
aria-pressed, an attribute specified whether the button is currently
pressed, would create a confusion. (Spoiler: it's everywhere).

See https://github.com/mastodon/mastodon/issues/13545#issuecomment-1304886969

app/javascript/mastodon/features/home_timeline/index.js

@@ -130,7 +130,6 @@ class HomeTimeline extends React.PureComponent {
           className={classNames('column-header__button', { 'active': showAnnouncements })}
           title={intl.formatMessage(showAnnouncements ? messages.hide_announcements : messages.show_announcements)}
           aria-label={intl.formatMessage(showAnnouncements ? messages.hide_announcements : messages.show_announcements)}
-          aria-pressed={showAnnouncements ? 'true' : 'false'}
           onClick={this.handleToggleAnnouncementsClick}
         >
           <IconWithBadge id='bullhorn' count={unreadAnnouncements} />