[TG Sync] Remove Local ID of shared tab groups during migration

This CL addresses an issue during rollback and reenabling of shared
tab group feature. During reenabling of the feature, when the shared
bridge and DB is read, it might have shared groups with non-empty
local IDs that are invalid now since the previous session with
shared tab group disabled should have closed those groups. Hence
these dangling local group IDs need to be cleared. This CL
does that as part of data read from the DB.

Bug: None
Change-Id: Ib6da6870b87e23cbd34e755e488fac2b227d3b95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6311400
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1426486}