Reduce the soft file descriptor limit to 10240

[OneBlue]

Summary of the Pull Request

This pull request solves a regression introduced in 2.5.7 causing docker's init.d script to fail to start

PR Checklist

• [X] Closes: Link to issue #12985 12985
• [ ] Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• [ ] Tests: Added/updated if needed and all pass
• [ ] Localization: All end user facing strings can be localized
• [ ] Dev docs: Added/updated if needed
• [ ] Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

We have increased the soft file descriptor limit to 1,048,576, and given that the hard file descriptor limit cannot be lower than the soft one (which is what ulimit -Hn 524288 is trying to do), that command fails.

Validation Steps Performed

Validated that docker successfully starts

[OneBlue]

/azp run

[azure-pipelines[bot]]

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