[TASK] Use TYPO3_version constant for Extbase help command

The output which version of Extbase is used, does not need to be
fetched via getExtensionVersion() of EXT:extbase. The TYPO3_version
contains the same information as the information in EXT:extbase/ext_emconf.php.

Resolves: #80438
Releases: master
Change-Id: I69be6c5949f39dac2c6a953d74c6cbfa7eaecd35
Reviewed-on: https://review.typo3.org/52150


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>