cmCTestBuildAndTestHandler: Simplify RunCMakeAndTest signature

Since commit 1a165dc60d (ENH: Move the build-and-test code to a handler,
2005-06-03, v2.4.0~1632), factored RunCMakeAndTest out of cmCTest, its
argument has been unnecessary.  In commit e60e4dfc88
(cmWorkingDirectory: Check success of current dir changes, 2018-03-04,
v3.12.0-rc1~395^2~1) unnecessary branching was added based on the
argument.  Remove both the argument and branching.