PageHeader: Fix title's leading padding in RTL environment

Flat is better than nested.
Sparse is better than dense.
Readability counts.
ⓒ The Zen of Python, by Tim Peters a.k.a. >>> import this

This extra smallSpacing was present in expression for LeftToRight layout direction, but was missing from RTL counterpart, probably due to how unreadable it was in a form of huge one-liner at that time. Reminder to always use small spacing in code, split it in comprehensible chunks :)

Amends adebba51 (well, kinda)

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Description	Before	After
Gallery RTL
Discover RTL
Discover "default" left-to-right no changes