(bug 45684) Don't count argument parsing time towards Lua limit

Currently, the time taken to parse the arguments passed to a Lua
function from #invoke will be counted against Lua's 10-second limit.
This is counterintuitive, and can remove incentive for users to convert
templates to Lua since they may have to convert a whole stack at once.

Note this requires change I11881232 to mediawiki/php/luasandbox to
actually have any effect.

Bug: 45684
Change-Id: I773950e4c399b8a1cfa6d1cde781a069d286b3bd