[TASK] Simplify returns in ConfigurationManager

writeLocalConfiguration() and writeAdditionalConfiguration()
have return statements like:
return $result === FALSE ? FALSE : TRUE;

This can be reduced to:
return $result;

Moreover the return value of canWriteConfiguration()
can be optimized as well.

Change-Id: I8e571459179e4bfeca3bba0a4969fb76d18058e2
Resolves: #54019
Releases: 6.2
Reviewed-on: https://review.typo3.org/25715
Reviewed-by: Markus Klein
Reviewed-by: Michiel Roos
Tested-by: Michiel Roos
Tested-by: Markus Klein
Reviewed-by: Oliver Klee
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe