RFR: 8186765: Speed up test sun/net/www/protocol/https/HttpsClient/ProxyAuthTest.java [v2]

[Daniel Jeliński]

> This PR reduces the execution time of ProxyAuthTest.
> 
> Before this change the test always required at least 3 minutes to complete (6x 30 seconds timeout in `SSLSocketTemplate`'s `sslServerSocket.accept()`).
> After this change the test does not open a server socket when it is not necessary.
> 
> The test continues to pass.

Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:

  Update copyright

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10539/files
  - new: https://git.openjdk.org/jdk/pull/10539/files/a814b593..6caee832

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10539&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10539&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10539.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10539/head:pull/10539

PR: https://git.openjdk.org/jdk/pull/10539