beta: Use scap-recompile from the scap git repo

Need to point /usr/local/bin/scap-recompile.

Due to some issue with the script provided by the scap repo, this change
depends on https://gerrit.wikimedia.org/r/#/c/120936/ to be merged..

Updates job beta-recompile-math-texvc

Change-Id: I328dc8bc58d869a3d651460de6920c2588c4d0d8