CodingStyleTest: run testXHTML for each business template

This will allow to find problems when only business templates and their
dependencies are installed. When we run testXHTML with all business
template installed we don't see problems that may happen only when some
business templates are not installed.
3 jobs for fix/testXHTML_by_bt in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-TestRunner1

00:43:17

failed ERP5.PerformanceTest-TestRunner1

00:32:06

failed ERP5.UnitTest-TestRunner1

01:18:11