[jdk11u-dev] RFR: 8288360: CI: ciInstanceKlass::implementor() is not consistent for well-known classes

[Goetz Lindenmaier]

I backport this for parity with 11.0.17-oracle.

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Commit messages:
 - Backport 50f99c3208fc9f479cc109fb6e73d262e27026a2

Changes: https://git.openjdk.org/jdk11u-dev/pull/1238/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1238&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288360
  Stats: 7 lines in 1 file changed: 2 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1238.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1238/head:pull/1238

PR: https://git.openjdk.org/jdk11u-dev/pull/1238