[TASK] Remove last bits of config.notification_*

Some TypoScript parameter were used in the old mail
handling and are now obsolete after latest deprecation
removals. The patch removes last bits of:

config.notification_email_charset
config.notification_email_encoding
config.notification_email_urlmode

Change-Id: I5d584a244e55407d6c98011e705f110c0eaf1f53
Resolves: #62793
Related: #62782
Releases: master
Reviewed-on: http://review.typo3.org/33919
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>