[jdk8u-dev] RFR: 8278067: Make HttpURLConnection default keep alive timeout configurable

[Dhamoder Nalla]

The JDK11 patch doesn't apply cleanly 1/4 hunks need to be ported manually.

Test performed:

1. JTreg jdk_tier1, hotspot_tier1
2. Testcase attached this PR

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Depends on: https://git.openjdk.org/jdk8u-dev/pull/407

Commit messages:
 - Backport d8f44aa39e921594505864e6270f42b745265293

Changes: https://git.openjdk.org/jdk8u-dev/pull/437/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=437&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8278067
  Stats: 261 lines in 4 files changed: 249 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/437.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/437/head:pull/437

PR: https://git.openjdk.org/jdk8u-dev/pull/437