[jdk11u-dev] RFR: 8282511: Use fixed certificate validation date in SSLExampleCert template

[Roman Marchenko]

clean backport

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Depends on: https://git.openjdk.org/jdk11u-dev/pull/1575

Commit messages:
 - Backport 268fa693188b685de6289927ee5a1e99473a50f6

Changes: https://git.openjdk.org/jdk11u-dev/pull/1576/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1576&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8282511
  Stats: 218 lines in 2 files changed: 37 ins; 2 del; 179 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1576.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1576/head:pull/1576

PR: https://git.openjdk.org/jdk11u-dev/pull/1576