RFR: CODETOOLS-7902943: jcstress: Update console UX again [v2]

[Aleksey Shipilev]

> We can make the console UX even better: print JVM/CPU in use counts, print sample frequencies, etc.

Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:

 - Fixes and refactorings
 - Remove excess method

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Changes:
  - all: https://git.openjdk.java.net/jcstress/pull/53/files
  - new: https://git.openjdk.java.net/jcstress/pull/53/files/7a94a234..2f4ce8ef

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jcstress&pr=53&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jcstress&pr=53&range=00-01

  Stats: 23 lines in 3 files changed: 5 ins; 12 del; 6 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/53.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/53/head:pull/53

PR: https://git.openjdk.java.net/jcstress/pull/53