Solve deprecations in t3org_layout

In order to update typo3.org to v9 as smoothly as possible, all extensions it requires should support v9 properly.

TYPO3Scanner result for t3org_layout:

Found 1 matches in 0.11s when checking for changes and deprecations in TYPO3 9

strong	weak	DEPRECATION
0.0% (0)	100.0% (1)	100.0% (1)

/Classes/Controller/SolrInstantSearchController.php
Call to method "connectToDB()" (weak)
39 $GLOBALS['TSFE']->connectToDB();
Deprecation: #84965 - Various TypoScriptFrontendController methods
https://docs.typo3.org/typo3cms/extensions/core/Changelog/9.3/Deprecation-84965-VariousTypoScriptFrontendControllerMethods.html

These deprecations should either be solved in the update branch develop-v9 directly, or have a Merge Request pointed to that branch in the typo3.org repository.