Update pre-receive secret detection CLI message

What does this MR do and why?

Issue: #456549 (closed)

Update pre-receive secret detection CLI message to match copy in #456549 (closed).

Note: The copy in the issue includes "To skip pre-receive secret detection, add the following git push option: --push-option=skip_secret_detection to your push command.". Currently, the actual CLI message includes "To skip pre-receive secret detection, include the text "[skip secret detection]" in a commit message for one of your changes, then push again.". The push option implementation is still a work in progress (issue: #435315 (closed)). This part of the CLI message will be updated when the issue is implemented.

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