[BUGFIX] Ensure correct initialization of selectTree value

This patch provides the current set database value in a hidden field as
early as the whole select tree JavaScript is provided. This prevents
data loss if the current record is saved before the select tree was loaded.

Resolves: #86954
Releases: master, 9.5, 8.7
Change-Id: I467b2a52d34b806713cd201a8a2a4f9bb8e92c71
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60415


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>