[jdk17] RFR: JDK-8249899: jdk/javadoc/tool/InlineTagsWithBraces.java uses @ignore w/o bug-id

[Jonathan Gibbons]

Also:
JDK-8249897: jdk/javadoc/tool/LangVers.java uses @ignore w/o bug-id
JDK-8249898: jdk/javadoc/tool/6176978/T6176978.java uses @ignore w/o bug-id

Please review a trivial PR for 17 to remove some tests which have been `@ignore`d since at least JDK 9.
The tests were previously written for the old API and doclet, and were at best incompletely updated for the new world.
The functionality covered by these tests is now better covered in other non-ignored tests, and there seems little benefit to trying to update them for the new world.

* InlineTagsWithBraces.java was about checking nested `{ }` inside inline tags, which is now covered by `doctree` tests for the `DocCommentParser`.
* LangVers.java was a JDK5-era test, ensuring that the right language level was assumed. This is now covered by delegating the relevant options (`-source`, `--release`, etc) to javac
* T6176978.java was about testing classloading of doclets. While we do not have any direct replacement tests, we have a variety of tests that load custom doclets, and javadoc uses the JavaFileManager API to get a class loader for the appropriate path.

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

Commit messages:
 - JDK-8249899: jdk/javadoc/tool/InlineTagsWithBraces.java uses @ignore w/o bug-id

Changes: https://git.openjdk.java.net/jdk17/pull/87/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=87&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8249899
  Stats: 333 lines in 4 files changed: 0 ins; 333 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/87.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/87/head:pull/87

PR: https://git.openjdk.java.net/jdk17/pull/87