Remove slugify text utility

**Why?**
This function was not being used and it's
documentation was out of date.

app/assets/javascripts/lib/utils/text_utility.js

@@ -43,13 +43,6 @@ export const pluralize = (str, count) => str + (count > 1 || count === 0 ? 's' :
  */
 export const dasherize = str => str.replace(/[_\s]+/g, '-');
 
-/**
- * Removes accents and converts to lower case
- * @param {String} str
- * @returns {String}
- */
-export const slugify = str => str.trim().toLowerCase();
-
 /**
  * Replaces whitespaces with hyphens and converts to lower case
  * @param {String} str

spec/frontend/lib/utils/text_utility_spec.js

@@ -49,12 +49,6 @@ describe('text_utility', () => {
     });
   });
 
-  describe('slugify', () => {
-    it('should remove accents and convert to lower case', () => {
-      expect(textUtils.slugify('João')).toEqual('joão');
-    });
-  });
-
   describe('capitalizeFirstCharacter', () => {
     it('returns string with first letter capitalized', () => {
       expect(textUtils.capitalizeFirstCharacter('gitlab')).toEqual('Gitlab');