Replace erikchen@ with isamsonov@ in test/launcher/OWNERS

Change-Id: I8b387723819d1fd138915b507eaac4624fd34917
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2042683
Auto-Submit: Erik Chen <erikchen@chromium.org>
Commit-Queue: Ilia Samsonov <isamsonov@google.com>
Reviewed-by: Ilia Samsonov <isamsonov@google.com>
Cr-Commit-Position: refs/heads/master@{#739116}

base/test/launcher/OWNERS

-erikchen@chromium.org
+isamsonov@google.com