Clean-up code in AjaxFormTrait

Problem/Motivation

FILE: /home/thallesvf/Desktop/lando/d8-contrib/modules/ctools/src/Form/AjaxFormTrait.php
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FOUND 3 ERRORS AFFECTING 3 LINES
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  1 | ERROR | [x] End of line character is invalid; expected "\n" but found "\r\n"
 16 | ERROR | [ ] Description for the @return value is missing
 31 | ERROR | [ ] Description for the @return value is missing
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Proposed resolution

Clear code on src/Form/AjaxFormTrait.php