Add tests for LogFormatter.format_data and format_data_short

[oscargus]

PR summary

Partly motivated by #26346

An interesting thing is that format_data_short use %-12g as formatter so the output is always zero-padded to 12 characters. This came in through bbbb267 as an attempt to make the cursor look better. However, it seems like no other format_data_short-method is doing this.

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• Plotting related features are demonstrated in an example
• New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines