[Feature] Move UseEtcdWrapper alpha feature to beta feature

[ishan16696]

Feature (What you would like to be added):

• Move UseEtcdWrapper alpha feature to beta feature by setting it as the default option in etcd-druid. Move feature:etcd-wrapper from alpha to beta feature. #744
• Remove the prow job: pull-etcd-druid-e2e-kind-alpha-features-true which runs etcd-druid e2e tests with feature gates turned on
  Added new prow job with feature gate turned off to run etcd-druid e2e tests with etcd-custom-image. ci-infra#1080
• Introduce new prow job that deactivates the UseEtcdWrapper feature gate (set UseEtcdWrapper=false). This is necessary for running druid end-to-end tests, as etcd-druid still needs to support the usage of etcd-custom-image.
  Added new prow job with feature gate turned off to run etcd-druid e2e tests with etcd-custom-image. ci-infra#1080

Motivation (Why is this needed?):
No issues has been observed in our canary landscape as of now, so etcd-druid can move UseEtcdWrapper feature to Beta.

Approach/Hint to the implement solution (optional):

[ishan16696]

/assign

[ishan16696]

All required PRs have been merged. Hence, closing this issue.
/close