chore(tests): replace __eq__() with diff() for detailed test diagnostics

[Molter73]

Description

When test assertions fail, the error messages now show exactly which fields differ between expected and actual events, rather than just displaying raw protobuf dumps. This significantly improves debugging efficiency by pinpointing the specific mismatches in process attributes, event types, paths, and event-specific fields.

Assisted-by: Claude Sonnet 4.5 noreply@anthropic.com

Checklist

• Investigated and inspected CI test results
• Updated documentation accordingly

Automated testing

• Added unit tests
• Added integration tests
• Added regression tests

If any of these don't apply, please comment below.

Testing Performed

Manually triggered an error in the test and got the following output:

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <server.FileActivityService object at 0x7fedd0d99400>, events = [<event.Event object at 0x7fedd0c446e0>], strict = True

    def _wait_events(self, events: list[Event], strict: bool):
        while self.is_running():
            msg = self.get_next()
            if msg is None:
                sleep(0.5)
                continue

            print(f'Got event: {msg}')

            # Check if msg matches any expected event
            diff = events[0].diff(msg)
            if diff is None:
                events.pop(0)
                if len(events) == 0:
                    return
            elif strict:
>               raise ValueError(json.dumps(diff, indent=4))
E               ValueError: {
E                   "file": {
E                       "expected": "/home/mmoltras/worktrees/fact/diff-on-failure/tests/fact-test-z9wg7j8k/create.txtother",
E                       "actual": "/home/mmoltras/worktrees/fact/diff-on-failure/tests/fact-test-z9wg7j8k/create.txt"
E                   }
E               }