[EuiPopover] Remove arrow pointer

[ryankeairns]

Note

In-progress work to update shadow tokens can proceed independently of this change.

Discussed in #8831

^{Originally posted by ryankeairns June 27, 2025}
This feels outdated... is it necessary? can we remove it?

Current state

Example from Geist

Alignment considerations

If removed, we may want to limit alignment to edges and not the center (or only use the arrow when aligned center?)
...we have all the alignment options available today.

Possible solutions

1. Never show an arrow but keep center alignment options
2. Never show an arrow and remove center alignment options
3. Only show an arrow on center alignment options
4. Change defaults to hasArrow: false and `anchorPosition: 'downLeft' (make arrow opt-in)
5. Do nothing; leave as-is

Proposed solution

• Go with Option 1
• Draft a PR to test in EUI and Kibana
• Determine if/how to proceed with merging the changes