Show full time range in metrics dashboard

What does this MR do?

Time series charts in the metrics dashboard currently sets the x-axis bounds based on data irrespective of the requested time range. This MR forces the chart to display the entire time range with empty space.

Example:

If the time window is 2 days and data is present for 1 day:

Before: The chart bounds will be set to 1 day
After: The chart bounds will be set to 2 days along with empty space

Screenshots

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Before
After

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

Mentions: #42737 (closed)