RFR: 8357799: Improve instructions for JFileChooser/HTMLFileName.java [v2]

[Alexey Ivanov]

> The instructions for the `javax/swing/JFileChooser/HTMLFileName.java` test are still not as clear.
> 
> The file name in the instructions is rendered as HTML, which, I believe, is unexpected. It should be displayed as the plain text.
> 
> The instructions also say about file and directory which have HTML in their name; this was true in the initial version of the test in #24439 that created files and directories on the real file system. 
> 
> The final version of test uses a virtual file system that displays *three files*, there's no way to navigate.
> 
> I also clarified the instructions: look at how the file name of the first file is rendered in _the file pane_ and _the navigation combo box_ (**Look in** in Metal L&F).
> 
> In the `VirtualFileSystemView` class, I changed the name of the third file from `virtualFolder` to `virtualFile2.log`, and made the file array a field which ensures `getRoots` and `getFiles` return the same list.
> 
> 
> In addition to this, I reduced the number of rows allocated for the instructions. Since the instructions are in HTML format, the number of lines of HTML code makes no sense for determining the size.

Alexey Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  Correct the title of the test frames

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25455/files
  - new: https://git.openjdk.org/jdk/pull/25455/files/d6cebfd0..f0633abd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25455&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25455&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25455.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25455/head:pull/25455

PR: https://git.openjdk.org/jdk/pull/25455