Fix a ConcurrentModificationException crash.

This is a pinpoint fix against the bug listed below. While a client
is synchronously reading the LinkProperties of a network, the
ConnectivityServiceThread is updating its properties. Make sure
that update is done atomically.

This is a stopgap countermeasure against a problem that is
pervasive with usage of LinkProperties, but fixing the problem
itself will happen later.

Clean cherry-pick of ag/4174798

Bug: 80077223
Test: runtest frameworks-net
Change-Id: I61b262d824c98b4ced36395a597b73de9193a199
Merged-In: I25007ac26349e451bb47f966af70d590d699c347
Merged-In: I03526187645b6955eb89ca4d2e4a930ebac236b8