RFR: 8297798: Timeout with DTLSOverDatagram test template [v2]

[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:

  cleaned up exception handling

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/11558/files
  - new: https://git.openjdk.org/jdk/pull/11558/files/fbe35671..85bc7c1d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11558&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11558&range=00-01

  Stats: 111 lines in 2 files changed: 18 ins; 64 del; 29 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