Fix vue render error for IDE status bar

What does this MR do?

When opening the IDE and there is no pipeline for the current branch, there is a Vue warning that ide_status_bar sent a Boolean to a String property (img-src). This also triggers a render error.

What was the fix?

Currently, state.latestPipeline can be one of the following values:

Value	Usage
null	The pipeline hasn't loaded yet (set in state.js)
false	The pipeline has loaded, but nothing was returned.
Object	The piepline has loaded.

Giving a semantic meaning to different falsey values hurts maintainability. This commit fixes the above problem by removing the false value and introducing a hasLoadedPipeline state property.

Screenshots

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Tests added for this feature/bug
• Tested in all supported browsers
• End to end tests added if this MR has ~"Requires e2e tests" label

Closes #59995 (closed)