Migrate PR testing from travis to GitHub actions [release-3.3]

[serathius]

Part of #13448

[ptabor]

Run echo "${TARGET}"
linux-amd64-integration-1-cpu
Running with TEST_CPUS: 1
Starting 'integration' pass at Mon Jan 17 14:59:43 UTC 2022
Running integration tests...
can't load package: package github.com/coreos/etcd/integration: cannot find package "github.com/coreos/etcd/integration" in any of:
	/opt/hostedtoolcache/go/1.12.12/x64/src/github.com/coreos/etcd/integration (from $GOROOT)
	/home/runner/go/src/github.com/coreos/etcd/integration (from $GOPATH)

Is it a wrong working directory where the command is being executed ?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.

[ahrtr]

3.3 is end of life, so we can close this PR?