[20589] Set real TCP non_blocking_send limitation

[jepemi]

Description

Since TCP actually allocates twice the size of the requested buffer, TCP non_blocking_send should not skip a send until this limit is reached. This PR doubles the limit from which a send should not be tried if TCP non_blocking_send is set to true.

@Mergifyio backport 2.13.x 2.12.x 2.10.x 2.6.x

Contributor Checklist

• [x] Commit messages follow the project guidelines.
• [x] The code follows the style guidelines of this project.
• [x] Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• N/A Any new/modified methods have been properly documented using Doxygen.
• [x] Changes are ABI compatible.
• [x] Changes are API compatible.
• N/A New feature has been added to the versions.md file (if applicable).
• N/A New feature has been documented/Current behavior is correctly described in the documentation.
• [x] Applicable backports have been included in the description.

Reviewer Checklist

• [ ] The PR has a milestone assigned.
• [ ] The title and description correctly express the PR's purpose.
• [ ] Check contributor checklist is correct.
• [ ] Check CI results: changes do not issue any warning.
• [ ] Check CI results: failing tests are unrelated with the changes.