SkinTemplate: Move debug HTML above bottomscripts

mediawiki.debug module, which is loaded at the bottom if
$wgDebugToolbar == true, depends on debug HTML (which sets some
mw.config stuffs with an inline script) being already present.

Bug: 56120
Change-Id: I5570fb4421e8e182fcf5e02754bf9ba6450be346
(cherry picked from commit 779badc31caf65e39b69b2a33b9f18d77a6a3618)