[Console] Testing: use explicit assertion assertCount instead of assertEquals

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

stumbled over this while batch cleaning tests for hhvm (which does not like `count` on objects - but this is not relevant here as its actually an array).