rerun failed openjdk tests with jdk_custom | hotspot_custon link should force set PARALLEL=None

[sophia-guo]

rerun failed openjdk tests with jdk_custom | hotspot_custon link fill most of parameters same as the current job. If the current job is a parents job of child job and it's parameter PARALLEL=Dynamic for rerun link the parameter should be set as None to avoid parallel mode. The reason is if there are too many testcases failure the rerun jdk_custom link won't work the suggestion is using the rerun failed target link. Rerun jdk_custom link works for quick rerun of a few test failures which doesn't need to run parallel.

[smlambert]

And also set RERUN_ITERATIONS=0