Default Rx Buffer change

[seguler]

What type of PR is this?

/kind feature

What this PR does / why we need it: Internal benchmarks revealed rx buffer of 2048 for 4 core or more machines outperformed in throughput tests and eliminated buffer related drops in Azure. It was determined that we'd change the default to 2048 for all customers who have more than 4 cores on their machines.

Which issue(s) this PR fixes: None

Requirements:

• [x] uses conventional commit messages perf: Performance Improvements 🚀
• [ ] includes documentation
• [x] adds unit tests
• [ ] tested upgrade from previous version
• [ ] commits are GPG signed and Github marks them as verified

Special notes for your reviewer:

Release note:

none