Merge pull request #58481 from dparmar18/wip-66771

src/test: test vectored/buffered sync i/o with buffers exceeding 2GiB in total len

Reviewed-by: Christopher Hoffman <choffman@redhat.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Rishabh Dave <ridave@redhat.com>