Remove reference to obsolete test target.
Remove reference to obsolete test target.

The safe_browsing_tests target doesn't exist anymore, so references in
the valgrind system to it can be removed.

BUG=69280

Review URL: https://codereview.chromium.org/1836283005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#384406}

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