Disable swarming for content_browsertests on Android.
Disable swarming for content_browsertests on Android.

BUG=585863

Review URL: https://codereview.chromium.org/1691513002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#374713}

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