Ensure service is reset after scenario test failures

[akouryy]

This PR fixes a bug in scenario_compiler.rb where core.reset! is not called when a test case fails. Due to this issue, one failing scenario can result in verbose failure messages that indicate irrelevant scenarios have also failed.

It seems that scenario_compiler.rb itself currently does not have test cases. While I have not added any in this PR, I will give it a try if requested.

Reproduction procedure

• Add scenario/a1.rb with the following content.

## update: test1.rb
f("a")

## assert
This is a wrong assertion.

• Add scenario/a2.rb with the following content.

## update: test2.rb
def f(x) = nil
f(0)

## assert
class Object
  def f: (Integer) -> nil
end

• Run rake test.

Expected Behavior

Only a1.rb fails.

Actual Behavior (prior to this PR)

a2.rb also fails, due to the code introduced by a1.rb.

Failure: test: scenario/a2.rb(ScenarioCompiler::ScenarioTest)
scenario/a2.rb:5:in `block in <class:ScenarioTest>'
<"class Object\n" + "  def f: (Integer) -> nil\n" + "end"> expected but was
<"class Object\n" + "  def f: (Integer | String) -> nil\n" + "end">

[mame]

Amazing! I've seen this problem many times, but never figured out how to fix it. Thank you!