Don't group testCases by benchmark/profile in comparison page

[rylev]

Fixes #1068

This changes the comparison page in two major ways:

• Test results are no longer grouped by benchmark/profile. Each test result exists independent of each other.
• The raw results (which are less important than the percent change and significance factor) are moved to the end of each row.

I don't love how this looks, but I think the overall behavior is an improvement. Any thoughts on how we can make this look better?

[Mark-Simulacrum]

I think we should make the raw results be right-aligned with each other to ease comparison if we're going to lay them out like this.

I think moving the scenario to its own column might be a good idea too, like it was before -- it helps me to be able to quickly scan to see what the major regression 'categories' are, and doing that in interleaved text is harder.

[rylev]

How about this?

[Mark-Simulacrum]

Works for me! I don't have a strong opinion on whether the raw data columns should be last or first but we can iterate on that based on how this works out.

r=me