[Serialization] DisableDeserializationOfExplicitPaths in the compiler by default
GH88239 demonstrates a problem with having this on by default in the
compiler, because the additional discovery of dependencies can lead to
an unexpected import of an implementationOnly dependency when
importing a module as a dependency.
This code no longer exists on the main branch.
This patch adresses the issue by only turning on explicit dependency
discovery when in LLDB, thereby reverting to the original module
loading behavior.
Fixes https://github.com/swiftlang/swift/issues/88239