RFR: JDK-8295859: Update Manual Test Groups

[Bill Huang]

This task is created to add manual tests to the manual test groups.

In addition, fix is provided for TestMatrix.java#Downcall-F and TestMatrix.java#Downcall-T which are failing due to missing TestDowncall.java ([JDK-8287158](https://bugs.openjdk.org/browse/JDK-8287158)).

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Commit messages:
 - Updated Manual Test Groups

Changes: https://git.openjdk.org/jdk/pull/10864/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10864&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295859
  Stats: 42 lines in 2 files changed: 35 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/10864.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10864/head:pull/10864

PR: https://git.openjdk.org/jdk/pull/10864