We are detecting descriptor types of parsed descriptors by either
content or file name. In some cases, if we downloaded descriptors from
web servers, there is no file name. In other cases the file name can
match more than one descriptor type. It seems most robust to move the
file name checks to the end, which includes web server access logs and
OnionPerf analysis files.

It seemed like a good idea to decompress xz-compressed files before
handing over decompressed bytes to descriptor implementations.
However, our web logs expect descriptor bytes to be in compressed
form, and now they're unhappy about receiving uncompressed bytes.
Changing this back and teaching OnionPerf analysis files to expect
compressed bytes, too. Found by running CollecTor's unit tests.

Implements #34070.