[jdk11u-dev] RFR: 8265367: [macos-aarch64] 3 java/net/httpclient/websocket tests fail with "IOException: No buffer space available"

[Goetz Lindenmaier]

I want to downport this to jdk11u-dev so that downporting the follow up 
"JDK-8268714: [macos-aarch64] 7 java/net/httpclient/websocket tests failed"
is more simple.

I had to resolve the following parts:

Copyright in several files.

PlainHttpConnection.java  Change in a comment that was added in "8256459: java/net/httpclient/ManyRequests.java and java/net/httpclien..." does not apply. Skipped.

ProblemList: Tests removed were not problem listed.

PendingOperations.java: 
 * imports due to context changes
 * cleanup(): Changes from "8249786: java/net/httpclient/websocket/PendingPingTextClose.java fails very infrequently" are missing. I added the output to System.err from that change.

PendingPingTextClose.java: Different indentation and line breaking.

PendingPongTextClose.java: Different context.

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Commit messages:
 - Backport 24bf35f862e285eeca662b9829901c0f91d247d5

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/487/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=487&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265367
  Stats: 131 lines in 13 files changed: 84 ins; 18 del; 29 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/487.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/487/head:pull/487

PR: https://git.openjdk.java.net/jdk11u-dev/pull/487