(QENG-1033) Don't modify constants and properly support all Linux platforms in Perf

The danger is what happens when the list is wrong in either case.

If I've missed something in the "positive" list, the associated beaker test still runs, but no perf data is spit out and Doug is red-faced as he opens a maint PR.

If I've missed something in the "negative" list, there is potential for the test to blow up as we try to call "sar" on an unsupported platform.

In your example, you missed solaris. In the future, if we added support for an entirely new platform (such as Cisco or Arista) the negative case leads to the possibility of blowups where the positive case just leads to the possibility of a maintenance check-in (no blowups).

TL:DR It's safer to choose which platforms to run "sar" on instead of choosing which platforms to NOT run "sar" on.