RFR: 8297798: Timeout with DTLSOverDatagram test template [v3]

[Matthew Donovan]

> This fix is intended to address various time-out errors in tests that use DTLSOverDatagram as a test template. Based on test output from those bugs (JDK-8202059, JDK-8249562, JDK-8280185, JDK-8280186, JDK-8269887, JDK-8268899), this fix:
> 
> * refactors the class to only create one additional thread
> * adds a CountdownLatch so if the server thread doesn't start for some reason, it is reported quickly
> * cleans up code to remove a loop condition that never fired: tests always time-out before too many loop iterations
> * removes CipherSuite.java from ProblemList
> 
> Ran the following tests 200 times each with no failures.
> * open/test/jdk/javax/net/ssl/DTLS/ClientAuth.java
> * open/test/jdk/javax/net/ssl/DTLS/PacketLossRetransmission.java
> * open/test/jdk/javax/net/ssl/DTLS/RespondToRetransmit.java
> * open/test/jdk/javax/net/ssl/DTLS/InvalidCookie.java
> * open/test/jdk/javax/net/ssl/DTLS/CipherSuite.java

Matthew Donovan has updated the pull request incrementally with one additional commit since the last revision:

  formatting changes

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11558/files
  - new: https://git.openjdk.org/jdk/pull/11558/files/85bc7c1d..b4fc96ba

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11558&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11558&range=01-02

  Stats: 4 lines in 1 file changed: 0 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11558.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11558/head:pull/11558

PR: https://git.openjdk.org/jdk/pull/11558