[Build] Build libcxx on lldb ASAN/UBSAN bots

The preset for ubsan/asan buildbots include the
`buildbot_incremental_base` preset, which builds/runs
tests. But the tests now require libcxx to be built
since #66018

(cherry picked from commit 7893c8e69b25bab559f7942ae82387b47c4e1928)

Author: Michael137

utils/build-presets.ini

@@ -320,6 +320,7 @@ skip-early-swift-driver
 #===------------------------------------------------------------------------===#
 
 [preset: buildbot_incremental_base]
+libcxx
 test
 validation-test
 lit-args=-v --time-tests