Delete unused constant kConfigParameterSize.
Delete unused constant kConfigParameterSize.

Unused since cl https://codereview.webrtc.org/1426953003

BUG=None

Review-Url: https://codereview.webrtc.org/2766823004
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#17345}

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