[lldb] [testsuite] Enable forgotten -gsplit-dwarf for 2 testfiles

D63643 added these testfiles but some of the %t4dwo and %t5dwo builds
are the same as corresponding %t4 and %t5 builds. Fortunately the
testcases do PASS.

After just adding -gsplit-dwarf these both skeleton files:
  tools/lldb/test/SymbolFile/DWARF/Output/debug-types-expressions.test.tmp4dwo
  tools/lldb/test/SymbolFile/DWARF/Output/debug-types-expressions.test.tmp5dwo

were referencing to this one non-skeleton file:
  tools/lldb/test/SymbolFile/DWARF/debug-types-expressions.dwo

Surprisingly it does not affect the other test debug-types-basic.test
probably because it compiles to .o and then links it. While
debug-types-expressions.test compiles directly to an executable.

So fixed that while keeping the direct executable compilation.

Differential Revision: https://reviews.llvm.org/D76316