[jdk21] RFR: 8311689: Wrong visible amount in Adjustable of ScrollPane

[Alexey Ivanov]

This is a clean backport of [JDK-8311689](https://bugs.openjdk.org/browse/JDK-8311689) which is a regression from [JDK-8297923](https://bugs.openjdk.org/browse/JDK-8297923).

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> This pull request contains a backport of commit [b3f34039](https://github.com/openjdk/jdk/commit/b3f34039fedd3c49404783ec880e1885dceb296b) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Alexey Ivanov on 11 Jul 2023 and was reviewed by Phil Race, Harshitha Onkar and Sergey Bylokhov.

@prrace @honkar-jdk @mrserb

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Commit messages:
 - Backport b3f34039fedd3c49404783ec880e1885dceb296b

Changes: https://git.openjdk.org/jdk21/pull/111/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=111&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311689
  Stats: 98 lines in 2 files changed: 96 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk21/pull/111.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/111/head:pull/111

PR: https://git.openjdk.org/jdk21/pull/111