Reduce the time e2e tests take

[serathius]

What would you like to be added?

E2e tests are taking over 40 minutes now, we should keep them unver 30 minutes or even lower.

For the top test candidates to optimize use https://testgrid.k8s.io/sig-etcd-periodics#ci-etcd-e2e-amd64&graph-metrics=test-duration-minutes

Current state

• go.etcd.io/etcd/tests/v3/common.TestMemberAdd > 5 minutes
• go.etcd.io/etcd/tests/v3/common.TestMemberRemove > 2 minutes
• go.etcd.io/etcd/tests/v3/e2e.TestAuthority > 1.5 minutes
• go.etcd.io/etcd/tests/v3/e2e.TestRuntimeReconfigGrowClusterSize > 1 minute
• go.etcd.io/etcd/tests/v3/common.TestUserAdd_Simple > 1 minute
• go.etcd.io/etcd/tests/v3/common.TestLeaseGrantAndList ~ 50 seconds
• go.etcd.io/etcd/tests/v3/e2e.TestVerifyHashKVAfterCompact ~50 seconds
• go.etcd.io/etcd/tests/v3/e2e.TestMixVersionsSnapshotByMockingPartition ~ 40 seconds
• go.etcd.io/etcd/tests/v3/common.TestKVDelete ~ 40 seconds
• go.etcd.io/etcd/tests/v3/common.TestLeaseGrantTimeToLiveExpired ~ 35 seconds
• go.etcd.io/etcd/tests/v3/e2e.TestWatchDelayForManualProgressNotification ~ 35 seconds ...

Looking for someone to take a look at the top tests and propose improvements to reduce runtime

Why is this needed?

We should keep the test execution time low to ensure good contributor expirience.

[serathius]

/cc @ahrtr @jmhbnz @ivanvc /help