Obsolete searchbox override on Plone 6 (breaks header)

[laulaz]

Due to obsolete searchbox.pt override (https://github.com/collective/collective.solr/blob/1f53a5db8a7e67d2fb43b585b476f68711c177f7/src/collective/solr/browser/searchbox.pt), the header & search are "broken" on Plone 6.

Before installing collective.solr :

After installing collective.solr :

cc @tisto

[tisto]

@tisto I personally have no intention to put work into making c.solr work in Plone 6 classic. We just don't have any Plone Classic projects any longer. Though, I am more than happy to review, merge and release any PR that makes c.solr work in Plone 6 Classic.