Clean unnecessary 'localVue' in various specs on 'spec/frontend'

What does this MR do?

As described in &2360 (closed), cleans up our Jest tests from unnecessary localVue usage

Involved specs

• spec/frontend/confidential_merge_request/components/project_form_group_spec.js
• spec/frontend/contributors/component/contributors_spec.js
• spec/frontend/ide/components/ide_status_list_spec.js - only clean up localVue.extend
• spec/frontend/issuables_list/components/issuables_list_app_spec.js
• spec/frontend/issue_show/components/pinned_links_spec.js
• spec/frontend/operation_settings/components/external_dashboard_spec.js
• spec/frontend/releases/list/components/evidence_block_spec.js
• spec/frontend/serverless/components/environment_row_spec.js

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Source issue: #121748 (closed)