Change parameter used to pass test expectations file paths

We are planning to remove the expectations_file parameter of the
telemetry.project_config.ProjectConfig class. We will be using the
new parameter, expectations_files instead.

R=nednguyen@google.com

Bug: chromium:835690
Change-Id: Id1137016018ff6fecee2022d4bc40c63915da0ff
Reviewed-on: https://chromium-review.googlesource.com/c/1377179
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#616971}
2 files changed