DefaultAccessLogReceiver rotates access log with an incorrect date string when the rotation happens after restarting

Undertow DefaultAccessLogReceiver initilizes a new rotate file name with the current date at the start-up. Therefore, DefaultAccessLogReceiver rotates access log with an incorrect date string when the rotation happens after restarting. It's better to use the date last modified of default access log file as a rotate file name when the file already exists.