Add more test data variety, rename variables verbosely, and add changelog entry.

Makes test pass again and implements task-23215.
Changes a test descriptor to contain a second annotation.

Part of task-23215.

Fixes #23255.

Related to #23255.

Implements task20516.

Implements task20515.

Implements #22833.

This patch reverts a path change made in 8767c73d.

Fixes #22754.

Implements part of #21551.

Implements #22652.

Similar to other statistics lines, there's nothing particular
sensitive in these new padding-counts lines that would reveal the
bridge IP address or location.  We can simply copy them over.

Implements #22216.

We recently switched to downloading .tpf files from OnionPerf hosts,
and we ran out of functioning Torperf hosts, so let's remove the code
for downloading and merging Torperf files.  Part of #21272.

Implements #21272.

Implements #21535.

Fixes #21443.