RFR: 6230751: [Fmt-Ch] Recursive MessageFormats in ChoiceFormats ignore indicated subformats [v4]

[Justin Lu]

> Please review this PR which updates an incorrect code example in _java/text/ChoiceFormat_.
> 
> ChoiceFormat (and MessageFormat) provide an example of how to produce a pattern that supports singular and plural forms. The ChoiceFormat example is incorrect, as recursive MessageFormats produced by a ChoiceFormat subformat only recognize subformats defined through the MessageFormat pattern syntax, not through the subformats contained within the top level MessageFormat. 
> 
> In the original example,
> `Format[] testFormats = {fileform, null, NumberFormat.getInstance()};` could have been replaced with 
> `Format[] testFormats = {fileform, null, new ChoiceFormat("0#BROKEN")};` and the original output would have been the same.
> 
> This PR replaces the example with the one used in MessageFormat, which is correct. 
> 
> This PR also includes a drive-by fix to remove leftover `<blockquote>`s from a previous `@snippet` conversion.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  shorten wording

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16891/files
  - new: https://git.openjdk.org/jdk/pull/16891/files/47e91b3d..3c9a6324

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16891&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16891&range=02-03

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16891.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16891/head:pull/16891

PR: https://git.openjdk.org/jdk/pull/16891