Revert "[Video Capture, Test] Make tests requiring real webcam fail if it's not found"

This reverts commit dfeab488cdc95233b19b9edeedef3d0b7581b17e.

Reason for revert: Tests fail on Chromium WebRTC bots. Example: https://ci.chromium.org/buildbot/chromium.webrtc/Mac%20Tester/84091

Original change's description:
> [Video Capture, Test] Make tests requiring real webcam fail if it's not found
> 
> Use prefix "UsingRealWebcam_" for names of tests that require real webcam and
> add checking whether webcam is found or not.
> Accordingly, exclude such test cases from test suites for devices that have no
> camera.
> 
> Bug: 893494
> Test: Ran capture_unittests including UsingRealWebcam_ tests on Chromebox (guado)
>       and it failed.
> Test: Ran capture_unittests excluding UsingRealWebcam_ tests on Chromebox (guado)
>       and it passed.
> Test: Ran capture_unittests including UsingRealWebcam_ tests on Chromebook (kevin)
>       and it passed.
> 
> Change-Id: I5c91380b7674aeace6a7d1764f7fad31f02f8af7
> Reviewed-on: https://chromium-review.googlesource.com/c/1276407
> Commit-Queue: Keiichi Watanabe <keiichiw@chromium.org>
> Reviewed-by: Christian Fremerey <chfremer@chromium.org>
> Reviewed-by: Ben Pastene <bpastene@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#599097}

TBR=bpastene@chromium.org,chfremer@chromium.org,keiichiw@chromium.org

Change-Id: I282dc00ffad2ff6614e7dfab1a9404da85cf032a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 893494
Reviewed-on: https://chromium-review.googlesource.com/c/1278272
Reviewed-by: Henrik Grunell <grunell@chromium.org>
Commit-Queue: Henrik Grunell <grunell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599123}
11 files changed