[jdk11u-dev] RFR: 8219804: java/net/MulticastSocket/Promiscuous.java fails intermittently due to NumberFormatException

[Aleksey Shipilev]

Clean backport to stabilize the test and match `11.0.13-oracle`.

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Commit messages:
 - Backport 54dfd47fa838614926363ff0f9b5bbc91c3792d0
 - Backport eccfec498d4062b582282f3b73bba84206a36046

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/255/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=255&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8219804
  Stats: 32 lines in 1 file changed: 23 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/255.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/255/head:pull/255

PR: https://git.openjdk.java.net/jdk11u-dev/pull/255