Desugar default methods if required

Desugar default methods if requested by LOCAL_MIN_SDK_VERSION < 26.
Also remove --desugar_try_with_resources_if_needed=false, it is no
longer necessary if we always proguard against frameworks.jar.
Fixes d8 issues when it sees unexpected default methods that dx
was passing through.

Test: m checkbuild
Change-Id: I81796b452d5a70a951e175727953d4295ca32c0c