[EuiDatePicker] Can no longer change text in input

[cchaos]

I believe this to be a regression where some added focus-stealing means anytime the input is selected the popover steals the focus making it impossible to change the input text directly.

[thompsongl]

I don't think this was ever(?) possible except when when using keyboard navigation. I went back to v9.9.1 (a year ago) and the behavior is the same.

Worth noting that EuiDatePicker does not use EuiPopover, so we may have less control. But, stock react-datepicker does not force focus so there's something else going on with our fork.