interpreter_main compare should default to none

[proppy]

Describe the bug

By default interpreter_main set --compare to jit which end up compare every test result of the dslx interpreter w/ the jit'ed version of the same function.

While this is useful when working on the toolchain to verify that a given change has no impact on the JIT (or ir conversion), in practice this has little value to the developer as they are likely to only care about one result.

To Reproduce

bazel test //xls/examples/...

Expected behavior

The default should be --compare=none for both interpreter_main and dslx_test bazel rule, so that it only run the tests thru the interpreter.

[mikex-oss]

FYI, the bazel rule is already being changed for #1415

Change default comparison method to none to avoid confusing errors when multiple procs are defined in a test.