[TASK] Remove unused Bootstrap dependency from frontend request handler

Due to moving BE user authentication to a middleware, the Bootstrap
instance is no longer needed in the frontend request handler.

As the backend request handler is free of a Bootstrap dependency as well,
we can also remove the Bootstrap injection in Http\AbstractApplication.

The installer and legacy request handlers are unaffected:
 * The installer application instantiates the request handler on its own.
 * Legacy request handlers are dispatched by the legacy request handler
   middleware which keeps passing in a Bootstrap instance

Releases: master
Resolves: #83961
Related: #83959
Change-Id: I85552b4b1734cdf75d96395ae7610ab19f0bf29c
Reviewed-on: https://review.typo3.org/55795


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>