fix(content-search): fixed content search by title (dotCMS#32194)

Closes dotCMS#31969

### Proposed Changes
* This pull request includes a small change to the `ContentSelector.js`
file. The change removes the assignment of the `structureVelVar`
property in the `_renderSearchField` method, because it was already set
in `_structureDetailsCallback` method after a content type is selected
in the search window.
* This assignment removal also avoids setting `structureVelVar` to
undefined when `field['fieldStructureVarName']` is not set, that was
causing this issue.

Author: dsolistorres

dotCMS/src/main/webapp/html/js/dotcms/dijit/form/ContentSelector.js

@@ -366,7 +366,6 @@ dojo.declare(
 
             var fieldVelocityVarName = field['fieldVelocityVarName'];
             var fieldContentlet = field['fieldContentlet'];
-            this.structureVelVar = field['fieldStructureVarName'];
             var value = '';
 
             var type = field['fieldFieldType'];