Fix defaults of BaseCompilerProperties

* Edition and Deny_warnings should not be set when
  constructing a BaseCompilerProperties, or the
  initialized values will reject values inherited from rust_defaults.
* Use getEdition and getDenyWarnings to retrieve those properties
  with defaults from config.

Bug: 141699953
Test: mm in rust projects
Change-Id: Id1ae357caeaf656cd33732bf4e54920e206f4ead