<i18n dev> RFR: 8331879: Clean up non-standard use of /// comments in `java.base`

[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).

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Commit messages:
 - incorporate review comments
 - Merge remote-tracking branch 'upstream/master' into 8330177.dangling-java.base
 - JDK-8331879: Clean up non-standard use of /// comments in `java.base`

Changes: https://git.openjdk.org/jdk/pull/19130/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19130&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331879
  Stats: 117 lines in 25 files changed: 0 ins; 0 del; 117 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