Update mount_disks.sh

[pprado]

"/usr/share/google/safe_format_and_mount" DEPRECATED!

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[pmkc]

This was "fixed" by fetching the deprecated script in https://github.com/GoogleCloudPlatform/bdutil/commit/911d19db9dd3c3d7165b9cdecf42778deabd9470.

In this case we would rather preserve backwards compatibility than remove the deprecated dependency.