Move TestLegacyApfFilter and MockIpClientCallback to LegacyApfTest am: a4fa50e68e

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/3178979

Change-Id: I936b7f1791299211cbf2d6a7851656fd53783f71
Signed-off-by: Automerger Merge Worker <[email protected]>