RFR: 8342860: Fix more NULL usage backsliding [v3]

[Thomas Schatzl]

On Thu, 7 Nov 2024 08:32:16 GMT, theoweidmannoracle <duke at openjdk.org> wrote:

>> - Changed several "NULL" in comments to "null"
>> - Changed several `NULL` in code to `nullptr`
>
> theoweidmannoracle has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix backslides in test

Marked as reviewed by tschatzl (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/21826#pullrequestreview-2423710194