[instrumented_libraries] add thomasanderson as owner

He is suggested by Nico in
https://chromium-review.googlesource.com/c/chromium/src/+/1701624/2#message-a7daaee06d9a39661d505583614efd17929dbce6

Change-Id: Ib4920a0be79cfa19707e74a79fd2ee9fe63034f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1705889Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Evgenii Stepanov <eugenis@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678424}

third_party/instrumented_libraries/OWNERS

-glider@chromium.org
 eugenis@chromium.org
-
+glider@chromium.org
+thomasanderson@chromium.org