build(ci): Remove TravisCI

[billyvg]

Travis sprung some surprise billing changes on us, so we are now prioritizing removing TravisCI completely.

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	19.97 KB (-0.01% 🔽)
@sentry/browser - Webpack	20.8 KB (0%)
@sentry/react - Webpack	20.8 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	27.12 KB (-0.01% 🔽)

[billyvg]

cc @HazAT @kamilogorek

Some questions:

• is scripts/test.sh only used in CI, or is it used locally?
• the node version matrix was only run on pushes (not PRs), is that intentional? Should we remove the build and test jobs from the Build & Test workflow?
• there's a big discrepancy in run times for GHA vs Travis, are the GHA tests running everything (the logs are kind of hard to parse for me)
  vs
  

Anything else that I'm missing?

[billyvg]

Added timeouts to all tests as a run away job can eat up our capacity.

[billyvg]

Fixes this https://github.com/getsentry/sentry-javascript/runs/1594862346#step:6:57

[lobsterkatie]

LGTM!

[billyvg]

Possible gains to be had with lerna concurrency? #3153

[lobsterkatie]

Possible gains to be had with lerna concurrency? #3153

Small ones, yes, but I'm not sure it'll make much of a difference, sadly. If you look at the final two commits in that PR, one with concurrency and one without, and you compare test times, you do get a small savings - around 2 min for the higher versions of node and around 1 min for the lower versions. I actually had my local repo set up to test concurrently for a while. Then I had to change it back for some reason (I forget) and I haven't gotten around to putting it back because the savings isn't that significant.

In any case, unless you feel strongly, let's get this merged and worry about that separately. I was just looking at the package.json commands and there are a few other changes which perhaps could be made also... not to mention which, tooling is going to be reevaluated for the next major release (which should hopefully be soon™), so it may turn out to be a moot point.