[lldb] Fix and rename skipIfHostIncompatibleWithRemote

Fix and rename the broken and confusingly named decorator
skipIfHostIncompatibleWithRemote. The decorator is meant to skip test
which uses the inferior test build system (i.e. to build test inferiors)
to build host binaries (e.g. lldb drivers).

The decorator was broken on macOS, where the host and target platform
report macosx, but the decorator overwrote it with Darwin, resulting in
tests incorrectly being skipped.

The decorator was also missing on a handful of tests that use the
buildDriver helper, which this commit fixes as well.