7903890: jcstress: Rewrite/amend Singleton and Lazy primitives samples

[shipilev]

It is obvious we do not have a good narrative around these, so let's add some.

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Progress

• Change must not contain extraneous whitespace
• Change must be properly reviewed (1 review required, with at least 1 Committer)

Issue

• CODETOOLS-7903890: jcstress: Rewrite/amend Singleton and Lazy primitives samples (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jcstress.git pull/155/head:pull/155
$ git checkout pull/155

Update a local copy of the PR:
$ git checkout pull/155
$ git pull https://git.openjdk.org/jcstress.git pull/155/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 155

View PR using the GUI difftool:
$ git pr show -t 155

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jcstress/pull/155.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

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[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[mlbridge]

Webrevs

• 01: Full - Incremental (07503013)
• 00: Full (9ff92719)