varnishd now uses 64bit vxids and a new VSL format, with some tags
removed.

I did ponder to write a VSL log converter or come up with some other
deliverate way to somehow preserve the old log data in a regerssion
log in the new format.

But ultimately, it all seemed pretty much wasted effort. Let's just
start with a new log and regression test future changes.

I must admit that I only hat a bit of a superficial look at the log
files, but as we made no changes at all to varnishevent, I do not see
how they could have changed fundamentally.

varnish-post-7.3.README.rst cotains information on how the log was
created.