[jdk23] RFR: 8325369: @sealedGraph: Bad link to image for tag on nested classes

[Chen Liang]

Please review this build-only change that fixes the link to the SVG sealed graph by the `@sealedGraph` javadoc taglet. This affects JDK 23 ea documentation (as shown in #20122) and thus is backported.

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

Commit messages:
 - Backport d06d79c80980644df511cded0eb8bc0309d878d3

Changes: https://git.openjdk.org/jdk/pull/20141/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20141&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325369
  Stats: 11 lines in 1 file changed: 2 ins; 2 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/20141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20141/head:pull/20141

PR: https://git.openjdk.org/jdk/pull/20141