fix(browser): Reassign lastEventId while eliminating duplicate events.

[onurtemizkan]

Fixes: #4018

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	22.39 KB (+0.34% 🔺)
@sentry/browser - Webpack	23.37 KB (+0.29% 🔺)
@sentry/react - Webpack	23.4 KB (+0.3% 🔺)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	29.84 KB (+0.23% 🔺)

[kamilogorek]

Overall I think it might work fine. WDYT @getsentry/team-webplatform ?
We should also port it to integrations/dedupe in case someone is using it.

[AbhiPrasad]

I’m fine with this approach

[iker-barriocanal]

Can we add tests?

And a question: is it possible the following flow happens?

1. A duplicated event E is generated.
2. Another event F is generated.
3. The ID of event E is set as the last ID.
4. The latest event ID corresponds to E, instead of F.

[onurtemizkan]

Closing this, as lastEventId's behaviour needs to be clarified first (#4018 (comment)) and this is probably too specific.

@iker-barriocanal, thanks. I'm now working on a new PR to add a test suite for dedupe integration. 👍