[jdk11u-dev] RFR: 8302109: Trivial fixes to btree tests

[Amos Shi]

Backport of [JDK-8302109](https://bugs.openjdk.org/browse/JDK-8302109)

Unclean Backport:
- `test/hotspot/jtreg/vmTestbase/nsk/sysdict/vm/stress/btree/btree002/btree002.java`
- `test/hotspot/jtreg/vmTestbase/nsk/sysdict/vm/stress/btree/btree005/btree005.java`
- `test/hotspot/jtreg/vmTestbase/nsk/sysdict/vm/stress/btree/btree008/btree008.java`
- `test/hotspot/jtreg/vmTestbase/nsk/sysdict/vm/stress/btree/btree011/btree011.java`
  - For the 4 files above, the only difference is the `Copyright year` line.
  - Manually merged this line
  - These 4 files can be considered as `Clean`

Test Succeeded in local Dev Apple M1 Laptop

-------------

Commit messages:
 - Backport 97d0c8720d46de8bd1620de975f6de3ba3eea560

Changes: https://git.openjdk.org/jdk11u-dev/pull/2393/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2393&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302109
  Stats: 9 lines in 4 files changed: 1 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2393.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2393/head:pull/2393

PR: https://git.openjdk.org/jdk11u-dev/pull/2393