Change default buffer size for stream reader

[aishwaryabh]

Issue describing the changes in this PR

The buffer size for the stream reader was initially set to -1, but this causes issues in .NET framework 4.8 as it expects a positive number. Looking at the source code for .NET framework 4.8, the default value is set to be 1024 if legacy isn't enabled. I also see in the documentation here that the default is set to be 1024 for later .NET versions.

resolves #issue_for_this_pr

Pull request checklist

• [x ] My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• [x ] My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• [x ] My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x ] I have added all required tests (Unit tests, E2E tests) (not needed since this is a bug fix)