Conferees Ban Lease of Boeing Tankers  WASHINGTON (Reuters) - House and Senate conferees agreed  late on Thursday to ban the leasing of aerial refueling  aircraft as part of a final deal on a \$422 billion defense  authorization bill, killing a proposed \$23.5 billion Air Force  deal with Boeing Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=BA.N target=/stocks/quickinfo/fullquote"&gt;BA.N&lt;/A&gt;, congressional sources said.