v.io/x/devtools/jiri-test: exclude flaky 3rd party go test.
v.io/x/devtools/jiri-test: exclude flaky 3rd party go test.

golang::org/x/crypto/ssh/test::TestCertLogin is flaky, so
we exclude it form our go tests.

Change-Id: I544ef03f136f6361a2e0dc60ee67f2a1f750c92e

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools