[Forwardport] Fix - Next Page button triggered when filtering Customer grid

[ronak2ram]

Description

I do change in grid.phtml. There is a missing button type. If we did not put button type then button work as a submit button.

Fixed Issues (if relevant)

1. Next Page button triggered when filtering Customer grid #17789: Next Page button triggered when filtering Customer grid

Manual testing scenarios

1. Go to "Sales -> Orders"
2. "Create new order"
3. Customer grid is displayed
4. Focus on any column filter (i.e. text box in email column)
5. Press ENTER to trigger the filter

Expected result

1. Filter's AJAX call is triggered
2. Results don't change because the filter input was empty
3. Grid is still showing the same page.

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)

Original PR

#17870

[magento-engcom-team]

Hi @ronak2ram. Thank you for your contribution
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[magento-engcom-team]

Hi @miguelbalparda, thank you for the review.
ENGCOM-2919 has been created to process this Pull Request

[magento-engcom-team]

Hi @ronak2ram. Thank you for your contribution.
We will aim to release these changes as part of 2.3.0.
Please check the release notes for final confirmation.