Use link_to helper instead of interpolated links

What does this MR do and why?

Use link_to helper instead of interpolated links

related to: #419672 (closed)

Screenshots or screen recordings

_import_group_from_another_instance_panel.html.haml

Before	After
<a href="/admin/application_settings/general#js-visibility-settings">enable it in the Admin settings</a>	<a href="/admin/application_settings/general#js-visibility-settings">enable it in the Admin settings</a>
<a href="/help/user/group/import/index.md#migrated-group-items" target="_blank" rel="noopener noreferrer">What items are migrated</a>	<a target="_blank" rel="noopener noreferrer" href="/help/user/group/import/index.md#migrated-group-items">What items are migrated</a>
<a href="/help/user/profile/personal_access_tokens" target="_blank">user settings</a> <a href="/help/security/token_overview#security-considerations" target="_blank">security reasons</a>	<a target="_blank" href="/help/user/profile/personal_access_tokens">user settings</a> <a target="_blank" href="/help/security/token_overview#security-considerations">security reasons</a>

app/views/projects/settings/integrations/index.html.haml

Before	After
<a href="http://gdk.test:3000/help/user/project/integrations/index">Integrations</a> <a href="/gitlab-org/webgoat.net/-/hooks">webhook</a>	<a href="http://gdk.test:3000/help/user/project/integrations/index">Integrations</a> <a href="/gitlab-org/webgoat.net/-/hooks">webhook</a>

app/views/projects/tags/new.html.haml

Before	After
<a href="/gitlab-org/webgoat.net/-/releases/new">New release page</a>	<a href="/gitlab-org/webgoat.net/-/releases/new">New release page</a>

app/views/shared/issuable/_form.html.haml

Before	After
<strong><a href="/gitlab-org/webgoat.net/-/blob/master/CONTRIBUTING.md">contribution guidelines</a></strong>	<strong><a href="/gitlab-org/webgoat.net/-/blob/master/CONTRIBUTING.md">contribution guidelines</a></strong>

app/views/users/_deletion_guidance.html.haml

Before	After
<a href="/help/user/profile/account/delete_account#associated-records">user account deletion documentation.</a>	<a href="/help/user/profile/account/delete_account#associated-records">user account deletion documentation.</a>

ee/app/views/admin/licenses/_breakdown.html.haml

Before	After
<a href="https://about.gitlab.com/pricing/licensing-faq/">true-up model</a>	<a href="https://about.gitlab.com/pricing/licensing-faq/">true-up model</a>
<a href="https://about.gitlab.com/pricing/licensing-faq/">users over license</a>	<a href="https://about.gitlab.com/pricing/licensing-faq/">users over license</a>
<a href="/help/subscriptions/self_managed/index#billable-users" target="_blank" rel="noopener noreferrer nofollow">billable users</a>	<a target="_blank" rel="noopener noreferrer nofollow" href="/help/subscriptions/self_managed/index#billable-users">billable users</a>

ee/app/views/groups/_custom_project_templates_setting.html.haml

Before	After
<a href="/help/user/group/custom_project_templates.md">Learn more</a>	<a href="/help/user/group/custom_project_templates.md">Learn more</a>

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.