[Unified Search Bar] Reduce height

[andreadelrio]

As part of the 9.0 release we're aiming to have a number of UI changes motivated by the introduction of the new theme Borealis. One of these changes is compressing the styles of Unified Search Bar which needs to happen on the Kibana side. @ryankeairns made a draft PR with these changes which can be found here.

Target outcome

To do

Compress Unified Search Bar styles to 32px of height.