CA-137044: XAPI shall handle the WLB disconfigure error according to CA-60147,CA-93312

During the investigation of CA-137044, we found the historical CA-60147 and CA-93312. 
So to fix CA-137044, we need restore XAPI to handle the WLB dis-configure error and this is per design.
To avoid future confuse, add one line comment.

Signed-off-by: Zheng Chai <zheng.chai@citrix.com>