[build-script] Cleanup the LLDB test phase
[build-script] Cleanup the LLDB test phase

This removes some redundant code from the LLDB test phase and simplifies
the remaining code. This is the first step in moving the test arguments
up to the CMake configuration phase, so we can just run check-lldb.

(cherry picked from commit 825a39abb3a9d5af44fb06cecbfe6687b8f4bda3)

lorentey/swift,jmgc/swift,JGiola/swift,tkremenek/swift,allevato/swift,ahoppen/swift,karwa/swift,tkremenek/swift,jmgc/swift,atrick/swift,allevato/swift,tkremenek/swift,xwu/swift,lorentey/swift,karwa/swift,karwa/swift,roambotics/swift,devincoughlin/swift,ahoppen/swift,nathawes/swift,benlangmuir/swift,allevato/swift,hooman/swift,harlanhaskins/swift,gregomni/swift,parkera/swift,glessard/swift,parkera/swift,rudkx/swift,benlangmuir/swift,sschiau/swift,JGiola/swift,atrick/swift,xwu/swift,benlangmuir/swift,aschwaighofer/swift,JGiola/swift,gribozavr/swift,xwu/swift,jmgc/swift,roambotics/swift,xwu/swift,gregomni/swift,apple/swift,allevato/swift,apple/swift,stephentyrone/swift,harlanhaskins/swift,aschwaighofer/swift,jmgc/swift,parkera/swift,rudkx/swift,nathawes/swift,stephentyrone/swift,glessard/swift,stephentyrone/swift,devincoughlin/swift,sschiau/swift,lorentey/swift,stephentyrone/swift,stephentyrone/swift,atrick/swift,nathawes/swift,lorentey/swift,gribozavr/swift,CodaFi/swift,harlanhaskins/swift,xwu/swift,jckarter/swift,xwu/swift,airspeedswift/swift,jckarter/swift,karwa/swift,allevato/swift,ahoppen/swift,devincoughlin/swift,tkremenek/swift,benlangmuir/swift,ahoppen/swift,gribozavr/swift,roambotics/swift,gregomni/swift,jmgc/swift,nathawes/swift,sschiau/swift,airspeedswift/swift,rudkx/swift,aschwaighofer/swift,aschwaighofer/swift,glessard/swift,parkera/swift,lorentey/swift,roambotics/swift,gribozavr/swift,jmgc/swift,allevato/swift,hooman/swift,lorentey/swift,xwu/swift,nathawes/swift,apple/swift,ahoppen/swift,ahoppen/swift,jckarter/swift,JGiola/swift,airspeedswift/swift,airspeedswift/swift,apple/swift,CodaFi/swift,hooman/swift,JGiola/swift,sschiau/swift,devincoughlin/swift,nathawes/swift,jckarter/swift,sschiau/swift,atrick/swift,aschwaighofer/swift,karwa/swift,benlangmuir/swift,gribozavr/swift,airspeedswift/swift,JGiola/swift,glessard/swift,jckarter/swift,glessard/swift,rudkx/swift,lorentey/swift,atrick/swift,CodaFi/swift,jckarter/swift,jmgc/swift,airspeedswift/swift,parkera/swift,CodaFi/swift,gregomni/swift,hooman/swift,jckarter/swift,stephentyrone/swift,sschiau/swift,tkremenek/swift,parkera/swift,karwa/swift,gregomni/swift,CodaFi/swift,harlanhaskins/swift,devincoughlin/swift,gribozavr/swift,atrick/swift,stephentyrone/swift,hooman/swift,parkera/swift,rudkx/swift,nathawes/swift,harlanhaskins/swift,devincoughlin/swift,rudkx/swift,benlangmuir/swift,harlanhaskins/swift,tkremenek/swift,sschiau/swift,aschwaighofer/swift,roambotics/swift,CodaFi/swift,harlanhaskins/swift,devincoughlin/swift,allevato/swift,gribozavr/swift,hooman/swift,karwa/swift,apple/swift,tkremenek/swift,devincoughlin/swift,hooman/swift,parkera/swift,CodaFi/swift,airspeedswift/swift,karwa/swift,apple/swift,sschiau/swift,aschwaighofer/swift,gribozavr/swift,lorentey/swift,glessard/swift,roambotics/swift,gregomni/swift