Fix lameduck API.
Fix lameduck API.

In Lameduck(), write a value to the RTC variable. Without this change, calling Lameduck() again on the same name, results in an error.

ORIGINAL_AUTHOR=Itamar Kaminski <itamark@google.com>
PiperOrigin-RevId: 182250154

cloudprober/cloudprober,cloudprober/cloudprober,cloudprober/cloudprober,google/cloudprober,google/cloudprober