Default emoji icon persists in issues and mrs header

What does this MR do?

Fixes a persistent emoji icon in issue and MR headers.

• Ensures we check show_emoji_status? in the issuable_meta method
• Adds related specs to issueables_helper_spec

Note: it's not currently possible for a user to set :speech_balloon: as their emoji status without setting the message or availability, see here and here

Screenshots (strongly suggested)

Before

With no status set, the default emoji is still appearing

Issues	Merge requests

After

Page	Without status set	With status
Issues
Merge requests

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

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

Related to #284601 (closed)