message: chore(percy): setting blank search placeholder in percy
  Percy was generating false positives with the placeholder text in
  snapshots, specifically for the story with the masthead search open.
  This will blank out the placeholder text in Percy only.
diff: @@ -179,7 +179,7 @@ withPlatform.story = {
  MastheadComposite: ({ groupId }) => ({
  hasProfile: boolean('show the profile functionality (has-profile)', true, groupId),
  hasSearch: boolean('show the search functionality (has-search)', true, groupId),
  - searchPlaceholder: textNullable('search placeholder (searchPlaceholder)', 'Search all of IBM', groupId),
  + searchPlaceholder: textNullable('search placeholder (searchPlaceholder)', inPercy() ? '' : 'Search all of IBM', groupId),
  selectedMenuItem: textNullable('selected menu item (selected-menu-item)', 'Services & Consulting', groupId),
  userStatus: select('The user authenticated status (user-status)', userStatuses, userStatuses.unauthenticated, groupId),
  }),
  