Rehome enable_d2d_connectivity_service Flag.

The flag enable_d2d_connectivity_service is moved from BetterTogether
module. This  allows us to hide the BetterTogether module from release
while the AOSP can still be compiled in release branches.

Bug: 517567152
Flag:android.bettertogether.flags.enable_d2d_connectivity_service
FCRS_CODE: mpq9ne35i2fn4a
Test: m
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:79f02f501cf603eeec85d728a0159ab9f139818b
Merged-In: I4af379c23beb598a5a6524c0994d84abc1ed42bb
Change-Id: I4af379c23beb598a5a6524c0994d84abc1ed42bb
2 files changed