[TASK] Only instantiate Locales in csConv when necessary

The locales property inside CharsetConverter is only
used for detecting the browsers' preferred language,
so it does not need to be instantiated on every TYPO3
request.

Resolves: #71805
Releases: master
Change-Id: I2de5591e75bb7b9dd3feaf2182d3502b0c7384a8
Reviewed-on: https://review.typo3.org/44932


Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>