Add diagnostics to testNativeDatagramTransmission

When the test fails, retry it 10 times, and an extra time on the
original source port. Report results in the connectivity diagnostics
file header so they can be parsed across tests.

This should help investigate issues possibly linked to UDP packets not
being routed properly depending on the port.

Test: atest
Bug: 375477810
Bug: 253698734
Bug: 324389407
Bug: 338090529
Change-Id: I8400b40257aa25a373c5a3ec96868d6877e0afb1
3 files changed