Change sdk_library child visibility semantics

If specified, the more specific *_visibility attribute override the
visibility attribute.

This is a temporary solution local to java_sdk_library. Ideally this
should be applied to all modules that create child modules.

Bug: 165017290
Test: m
Exempt-From-Owner-Approval: cherry-pick from master
Change-Id: Ia8c5ae119623a83d8ac583c602320915bb8c7f33
Merged-In: Ia8c5ae119623a83d8ac583c602320915bb8c7f33
(cherry picked from commit 944e77d2)