fix(replay): Use session.started for min/max duration check

[mydea]

We've been using context.initialTimestamp to check for min/max session duration, but actually this is always updated when a tab is refreshed, for example.

Instead, we now use session.started, which should also always be updated for a buffer session.

note that this also means, when an error happens, we flush immediately, but then wait for 5s until we flush again (which is fine, I'd say) - because at the time of conversion of buffer->session, we update the started of the session. But that's OK I'd say?

I also updated the logging to be based on this. Overall having a log for the buffer->session change makes sense to me anyhow, plus I also added one for the only other case where session.started is updated.

Note: I added a test to kind of cover this, but this test also passed with the previous version, so 🤷 not entirely sure how to test this better 😬

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	21.99 KB (-0.01% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	69.25 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	20.33 KB (-0.01% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	60.48 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	21.95 KB (0%)
@sentry/browser - Webpack (minified)	71.63 KB (0%)
@sentry/react - Webpack (gzipped + minified)	21.96 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	50.83 KB (0%)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	30.37 KB (-0.01% 🔽)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	28.24 KB (-0.01% 🔽)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	49.58 KB (+0.05% 🔺)
@sentry/replay - Webpack (gzipped + minified)	43.37 KB (+0.12% 🔺)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	69.76 KB (+0.05% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	62.04 KB (+0.05% 🔺)

[billyvg]

Does this test fail without the new changes?

[mydea]

No, sadly it does not 😬 I think it is because it still triggers the session refresh, as it should, this is kind of the root cause somewhere that this is under some (?) circumstances not happening. This change should be good/better anyhow, I'd say. And with the improved logging, we maybe get closer to the root of this!