[Stopwatch] Fix checking started events

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7639, #7653
| License       | MIT

Stopwatch component return true from isStarted method, when StopwatchEvent was added but not started.