[SB Refactor] Define a new buffer for the shared connectivity repo.

Since ConnectivityPiplineLogger will eventually become mobile only, we
need to add a different buffer for the shared repo.

Bug: 238425913
Test: make modifications via System UI Tuner, then `adb shell dumpsys
activity service com.android.systemui/.SystemUIService
SharedConnectivityInputLog` -> see tuner updates in log

Change-Id: I5b75bc5e09f176ce54264023f0fcf33eb52ed07a