FIX Truncate table to clear table

[emteknetnz]

Issue silverstripe/.github#278

For whatever reason MySQL 8 specifically would end up with an auto increment value of 2 instead of 1 which caused behat tests that rely on an ID to fail e.g. https://github.com/silverstripe/silverstripe-elemental/actions/runs/9986875108/job/27600180632?pr=1219

Truncating the table will correctly reset the auto increment

recipe-sink ci run with pr - https://github.com/creative-commoners/recipe-kitchen-sink/actions/runs/10005707377

[GuySartorelli]

Weird that the code here intended to resolve this wasn't resolving it - but even weirder we weren't already truncating. LGTM.

[robbieaverill]

It's possible that it was like this because truncating tables can fail if there are foreign key constraints in place, whereas deleting doesn't.

Background context here: #8437

Edit: you could remove this method overload entirely as it's now the same as the parent class

[emteknetnz]

Gah .. yeah Sam wasn't kidding about the performance difference when running phpunit

Before

After :(

Have raised issue to revert and reimplement - #11311