Merge "Move the delegated prefix validity check to IaPrefixOption class." into main am: a1eb2e453f

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2777291

Change-Id: I49c51cf143719b2ddc4d852eee5d2ae7c9133b56
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>