[EuiDataGrid] Cannot clear current "Lines per row" value to enter a new one

[davismcphee]

Describe the bug
When opening the "Display options" popover and setting "Row height" to "Custom", users are unable to clear out the "Lines per row" input value to type in another. Instead they must either use the slider, spinner, or highlight the current value and type over it.

Impact and severity
Low impact and severity. There are easy ways to work around it, and it's just an annoying UX paper cut.

Environment and versions

• EUI version: v90.0.0
• React version: 17.0.2
• Kibana version (if applicable): 8.12
• Browser: Chrome
• Operating System: macOS

To Reproduce
Steps to reproduce the behavior:

1. Go to any EUI data grid (e.g. Discover in Kibana).
2. Click on the "Display options" button.
3. Set "Row height" to "Custom".
4. Attempt to clear the "Lines per row" input value.
5. Observe that the value cannot be cleared.

Expected behavior
Allow the "Lines per row" input to be cleared out, then highlight the input as invalid, and if no valid value is entered, reset to the previous value upon dismissing the popover.

Minimum reproducible sandbox
Reproducible in any EuiDataGrid. Used the "Core concepts" example for the sandbox: https://codesandbox.io/s/5kw62m?file=/demo.js

Screenshots

lines_per_row.mp4

[cee-chen]

Gonna be annoying and mark this one an enhancement feature request - I don't consider it currently broken per se, but it's easy enough to implement/enhance. Will have a PR for it soon