RFR: 8331879: Clean up non-standard use of /// comments in `java.base` [v2]

[Jonathan Gibbons]

> With the advent of JEP 467, `///` comments may be treated as documentation comments, and may be subject to the recently new `javac` warning about "dangling doc comments" in unexpected places.
> 
> In keeping with the policy to keep the `java.base` module free of all `javac` warnings, this patch proposes edits to existing uses of `///`.
> 
> There are two dominant policies in the proposed changes. 
> 1. A long horizontal line of `/////` is replaced by `//-----`
> 2. A long vertical series of lines beginning `///` is replaced by lines beginning `//|`.
> 
> As with all style changes, I have also tried to honor local usage, for consistency.
> 
> In one place, a pair of comments appeared to contain directives (`CLOVER:ON`, `CLOVER:OFF`).  I investigated the use of such comments to determine that the exact form of the comment prefix was not significant. (Phew!)
> 
> 
> (This PR is informally blocked by JEP 467).

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  incorporate review comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19130/files
  - new: https://git.openjdk.org/jdk/pull/19130/files/3e039b43..e77a4d14

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19130&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19130&range=00-01

  Stats: 24 lines in 7 files changed: 0 ins; 0 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/19130.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19130/head:pull/19130

PR: https://git.openjdk.org/jdk/pull/19130