Update code to use less CSS

- use humanize method to prepare strings
- remove unnecessary backticks

ee/app/assets/javascripts/vue_shared/security_reports/store/utils/convert_report_type.js

 import { REPORT_TYPES } from 'ee/security_dashboard/store/constants';
+import { humanize } from '~/lib/utils/text_utility';
 
 /**
  * Takes the report type, that is not human-readable and converts it to be human-readable
  * @param {string} reportType that is not human-readable
- * @returns {string} the conversion from REPORT_TYPES or a lowercase version without '_' in it to
- *                   be paired with the CSS class `text-capitalize`
+ * @returns {string} a human-readable version of the report type
  */
 const convertReportType = reportType => {
   if (!reportType) return '';
   const lowerCaseType = reportType.toLowerCase();
-  return REPORT_TYPES[lowerCaseType] || lowerCaseType.split('_').join(' ');
+  return REPORT_TYPES[lowerCaseType] || humanize(lowerCaseType);
 };
 
 export default convertReportType;

ee/app/assets/javascripts/vulnerabilities/components/vulnerability_list.vue

@@ -112,7 +112,7 @@ export default {
           key: 'reportType',
           class: this.reportTypeClass,
           label: s__('Reports|Scanner'),
-          thClass: `${commonThClass}`,
+          thClass: commonThClass,
         },
       ];
     },

ee/spec/frontend/vue_shared/security_reports/store/utils_spec.js

@@ -50,9 +50,9 @@ describe('security reports utils', () => {
       ['sast', 'SAST'],
       ['dependency_scanning', 'Dependency Scanning'],
       ['CONTAINER_SCANNING', 'Container Scanning'],
-      ['CUSTOM_SCANNER', 'custom scanner'],
-      ['mast', 'mast'],
-      ['TAST', 'tast'],
+      ['CUSTOM_SCANNER', 'Custom scanner'],
+      ['mast', 'Mast'],
+      ['TAST', 'Tast'],
       [undefined, ''],
     ])('converts the report type "%s" to the human-readable string "%s"', (input, output) => {
       expect(convertReportType(input)).toEqual(output);

ee/spec/frontend/vulnerabilities/vulnerability_list_spec.js

@@ -194,7 +194,7 @@ describe('Vulnerability list component', () => {
       const cells = findCells('reportType');
       expect(cells.wrappers[0].text()).toBe('SAST');
       expect(cells.wrappers[1].text()).toBe('Dependency Scanning');
-      expect(cells.wrappers[2].text()).toBe('custom scanner without translation');
+      expect(cells.wrappers[2].text()).toBe('Custom scanner without translation');
       expect(cells.wrappers[3].text()).toBe('');
     });
   });