Describe the bug
When giving hasShadow and/or hasBorder to the popover panel via the panelProps prop, you don't get the expected results. For example, when giving panelProps={{ hasShadow: false }} as a prop to EuiPopover...

Actual	Expected

Environment and versions

• EUI version: 81.0.0
• Browser: Chrome

To Reproduce
Steps to reproduce the behavior:

1. Create an EuiPopover component and add panelProps={{ hasShadow: false }} as a prop
2. Open the popover and notice that the shadow is still present 🔥

and/or...

1. Create an EuiPopover component and add panelProps={{ hasBorder: true }} as a prop
2. Open the popover and notice that the panel does not have a border 🔥

Minimum reproducible sandbox
https://codesandbox.io/s/vibrant-tree-wc5i7g?file=/demo.js