RFR: 8285951: Replace Algorithms.eatMemory(...) with WB.fullGC() in vmTestbase_vm_gc_ref tests [v2]

[Leonid Mesnik]

> remainging weak/soft/phantom reference tests are updated to use WB.fullGC()
> 
> The TEST.properties are removed for single-threaded tests.

Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:

  more attepmts of WB.GC() added to multi-threaded tests.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8474/files
  - new: https://git.openjdk.java.net/jdk/pull/8474/files/bffb295b..b49e2415

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8474&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8474&range=00-01

  Stats: 44 lines in 3 files changed: 25 ins; 9 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8474.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8474/head:pull/8474

PR: https://git.openjdk.java.net/jdk/pull/8474