WIP: Increase width of multi-metric embeds

What does this MR do?

There is an issue where single multi-metric embeds don't expand to fill the width of the page when there is room to. This MR fixes this.

issue: #214276 (closed)

Screenshots

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

Additional:

• Test with dashboard link (e.g. http://0.0.0.0:3001/root/tr-test-proj/-/environments/29/metrics/?dashboard=config%252Fprometheus%252Fcommon_metrics.yml).
• Test with single metric.
• Test with multi metric.
• Test with parameterised chart (e.g. NGINX Response Metrics).
• Test with a combination of the above.

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