[TASK] Make use of .t3-table in EXT: belog

Use <table class="t3-table"> in backend module.

Change-Id: I8f4f51020e8bf5140144d296172ab06c92bf8d6b
Resolves: #52565
Releases: 6.2
Reviewed-on: https://review.typo3.org/24434
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn