6802: Magento\Search\Helper\getSuggestUrl() not used in search template.

[nmalevanec]

Description

Magento\Search\Helper\Data::getSuggestUrl() now used in form.mini.phtml instead of direct call on $block->getUrl().

Fixed Issues (if relevant)

1. Magento\Search\Helper\getSuggestUrl() not used in search template #6802: Magento\Search\Helper\getSuggestUrl() not used in search template

Manual testing scenarios

1. Create a plugin for Magento\Search\Helper\Data::getSuggestUrl() with method afterGetSuggestUrl() to add custom autosuggest feature(or use just return 'some-test-url-which-leads-nowhere').
2. Type something in the search box.
3. the custom URL should be used(check console, if you use 'some-test-url-which-leads-nowhere'. You should see 404 error with your test url with query params).

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)