Update VPN isolation code for excluded routes

Bug: 230058738
Test: atest LinkPropertiesTest

Result: https://paste.googleplex.com/4706859672928256

Change-Id: I970fca6b0e2cd358e9bd77152563d13367867c74
(cherry picked from commit 2b97bbebf4b85e0024fc75298e760fc03516be40)
Merged-In: I970fca6b0e2cd358e9bd77152563d13367867c74
3 files changed