ref(serverless): Do not throw on flush error

[lforst]

There is a number of issues on the fact that we fail or stall serverless functions when anything goes wrong while flushing:

• AWS Lambda failing on Sentry failures #4862
• [GCPFunction] Failure to flush leads to cloud function hanging #4809
• falsy reason in tests when using serverless AWSLambda.wrapHandler #3133

Considering our fire & forget mantra for events, this PR changes the behaviour of our lambda/cloud function wrappers to catch and log errors that occur while flushing. Up until now we threw upwards if something went wrong while flushing.

Todo after merging: Remove https://docs.sentry.io/platforms/node/guides/aws-lambda/#ignore-sentry-errors section

Ref: https://getsentry.atlassian.net/browse/WEB-918

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	18.75 KB (-6.91% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	58.19 KB (-9.95% 🔽)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	17.49 KB (-7.26% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	52.43 KB (-9.56% 🔽)
@sentry/browser - Webpack (gzipped + minified)	19.33 KB (-16.84% 🔽)
@sentry/browser - Webpack (minified)	61.44 KB (-24.82% 🔽)
@sentry/react - Webpack (gzipped + minified)	19.35 KB (-16.88% 🔽)
@sentry/nextjs Client - Webpack (gzipped + minified)	42.81 KB (-10.92% 🔽)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	24.41 KB (-6.4% 🔽)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	22.95 KB (-6.25% 🔽)