VCN: Explicitly handle IAE from updating underlying network

IpSecTunnelInterface#setUnderlyingNetwork will throw IAE when the
underlying network is not functional and has null LinkProperties.
This commit updates VCN to explicitly handle this exception, instead
relying on the mechanism for handling all uncaught exceptions.

Bug: 240112879
Test: atest CtsVcnTestCases & FrameworksVcnTests
Change-Id: I2fdf1da542eb04d56a04e04c762f8c2c19828071