Remove 'direction: ltr' from 'pre' styles

The 'direction' and 'unicode-bidi' rules must not be made default.
Right-to-left languages can use preformatted text too!

Follow-up to 054b1c9e3cd82ee96bb6ee2be3026497e5f9f099.

(Also linked T2260, which that commit fixed.)

Bug: T103780
Change-Id: Ieab6b1473e6ce0faed3617d11e57cd2b4f3ef6df