[TASK] Correct @deprecation of isLastPartOfString()

The @deprecation annotation of StringUtility::isLastPartOfString says:

@deprecated since 7.0, use beginsWith() instead
correct would be
@deprecated since 7.0, use endsWith() instead

Further a small change in the phpDoc of beginsWith() to assimilate it with
endsWith()

Resolves: #62810
Releases: master
Change-Id: I69f6ce00980a97abe1c0e7c6f28e44acedc6214c
Reviewed-on: http://review.typo3.org/33940
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>