[dPWA Testing] Removing default params, fixing SwitchProfile args

This change removes the default params which are populated by the
script, and fixes the SwtichProfileClients method to accept a mode.

This also encorporates changes to the SwitchProfileClients to have
shorter mode name.

Bug: 1215791
Change-Id: Ia12e745f3a2b737a6524163184b6f6481d256a26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3134239
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Auto-Submit: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Phillis Tang <phillis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#918968}