[BUGFIX] Fix positioning of progress bars in Extension Scanner module

With the upgrade to Bootstrap 5, the panels have no explicit position
anymore, breaking the progress bars in the Extension Scanner found in
the Install Tool.

This commit adds a relative positioning to the panels.

Resolves: #104073
Releases: main, 12.4
Change-Id: Ie67989dbcfa859ebc3020dabaa27913de7ae4b64
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84663


Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>