Remove non-default wrap setting for markdown (#14304)

With this setting, markdown files are one of the few that get a line
wrap indicator, a vertical line on the right, which confuses people.

Release Notes:

- N/A

crates/languages/src/markdown/config.toml

@@ -13,5 +13,4 @@ brackets = [
 ]
 
 tab_size = 2
-soft_wrap = "preferred_line_length"
 prettier_parser_name = "markdown"