Avoid checking for raw data if visits log is disabled

[sgiehl]

Description:

When a report page has no data, we currently use Live.getLastVisitsDetails to determine if any raw data is available.
If that is the case we show a notification that explains, that data was not yet processed and that the visits log can show whats currently happening on the site.

In case the visits log is disabled, the Live.getLastVisitsDetails throws an error, which might then be displayed to the user.
As there is no sense in suggesting the user to look at the visits log if it's disabled, this PR simply disables the check for raw data in that case.

fixes #20948

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed