java_sdk_library: Remove unnecessary qualification of fields

Fields in embedded structures can be accessed without qualifying them
by the type of the embedded structure.

This reduces the size of follow up changes that switch java_sdk_library
from embedding Library.

Bug: 156618935
Test: m nothing
Merged-In: I84f294c6f02d5089055130c63f5fb0538a1f21b9
Change-Id: I84f294c6f02d5089055130c63f5fb0538a1f21b9
(cherry picked from commit a18abc2a)