ere can be
      multiple connections to the given server using different user mappings.
      If the connections are used in the current local transaction,
      they are not disconnected and warning messages are reported.
      This function returns <code class="literal">true</code> if it disconnects
      at least one connection, otherwise <code class="literal">false</code>.
      If no foreign server with the given name is found, an error is reported.
      Example usage of the function:
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