[Backport] Checkout page - Fix tooltip position on mobile devices

[ihor-sviziev]

Original Pull Request

#14678

Description

Fix tooltip position on mobile devices on checkout page

Fixed Issues (if relevant)

N/A

Manual testing scenarios

1. Go to checkout page on mobile device
2. Click to "?" icon near "email" or "phone" inputs

Expected result

Tooltip should be visible, additional scroll should not be added

Actual result

Tooltip should is visible, but additional scroll is added

Notes

1 . Fixes were split into two commits to be able apply patch while fix is not released yet.
2. Issue is caused by usage different @brake variables in

magento2/app/design/frontend/Magento/blank/Magento_Checkout/web/css/source/module/checkout/_tooltip.less

Lines 141 to 147 in 1224795

	.media-width(@extremum, @break) when (@extremum = 'max') and (@break = @checkout-tooltip-breakpoint__screen-m) {
	.field-tooltip {
	.field-tooltip-content {
	&:extend(.abs-checkout-tooltip-content-position-top-mobile all);
	}
	}
	}

and https://github.com/magento/magento2/blob/1224795/app/design/frontend/Magento/blank/web/css/source/_extends.less#L1236-L1240

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)

[magento-engcom-team]

Hi @ihor-sviziev. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.1.15 release.