Migrate HAML buttons to Pajamas in app/views/profiles/keys

What does this MR do?

Migrates HAML buttons to Pajamas in app/views/profiles/keys.

Related to #231210 (closed)

Screenshots

Before	After

Note: the button has a minor visual change as expected.

Files in directory with buttons that needs migration

• app/views/profiles/keys/_form.html.haml
• app/views/profiles/keys/_key.html.haml
• app/views/profiles/keys/_key_details.html.haml

The last two files have been left unchanged because they use gl-button and seem to have been migrated already.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides

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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #231210 (closed)