Upgrade/Install: Correct vertical alignment for "Continue" button on language...

Upgrade/Install: Correct vertical alignment for "Continue" button on language selection during the install process.

Props garrett-eclipse, audrasjb.
Fixes #49018.
Built from https://develop.svn.wordpress.org/trunk@47070


git-svn-id: https://core.svn.wordpress.org/trunk@46870 1a063a9b-81f0-0310-95a4-ce76da25c4cd