[lldb] build: cleanup extraneous include paths (#117615)

Clean up some unnecessary include paths. The use of `LibXml2::LibXml2`
with `target_link_libraries` on `libLLDBHost` ensures that the header
search path is properly propagated.

GitOrigin-RevId: 24593f1814dc02c7404526674838ccfb1c61d780
1 file changed