Remove beccahughes@google.com from src/com/android/settings/applications/credentials/OWNERS

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memberships and affiliations.
If this change is unnecessary or in error, vote CR -1 and the bot
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See the owner's recent activity for context:
https://android-review.googlesource.com/q/beccahughes@google.com

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Change-Id: I8563f73848a4e32ff3da4b1eaf34253374d9012c