feat: Switching to DevWorkspace engine by default

[tolusha]

What does this PR do?

Switching to DevWorkspace engine by default:

• removes tech-preview channels
• set devworkspace.enable: true by default
• adopt tests scripts
• remove keycloak support
• remove code related to deprecated failds from, see Simplify Eclipse Che configuration format (CheCluster API v2) che#20758

Screenshot/screencast of this PR

N/A

What issues does this PR fix or reference?

eclipse-che/che#20866

How to test this PR?

See PR checks

PR Checklist

As the author of this Pull Request I made sure that:

• The Eclipse Contributor Agreement is valid
• Code produced is complete
• Code builds without errors
• Tests are covering the bugfix
• Custom resource definition file is up to date
• OLM bundles are up to date
• The repository devfile is up to date and works
• Sections What issues does this PR fix or reference and How to test this PR completed
• Relevant user documentation updated
• Relevant contributing documentation updated
• CI/CD changes implemented, documented and communicated

Reviewers

Reviewers, please comment how you tested the PR when approving it.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[codecov]

Codecov Report

Merging #1249 (f0c979b) into main (f0bb5ae) will increase coverage by 3.80%.
The diff coverage is 25.00%.

@@            Coverage Diff             @@
##             main    #1249      +/-   ##
==========================================
+ Coverage   56.77%   60.57%   +3.80%     
==========================================
  Files          84       81       -3     
  Lines        8728     7465    -1263     
==========================================
- Hits         4955     4522     -433     
+ Misses       3275     2489     -786     
+ Partials      498      454      -44     

Impacted Files	Coverage Δ
pkg/deploy/defaults.go	45.58% <ø> (-0.13%)	⬇️
pkg/deploy/dev-workspace/dev_workspace.go	55.55% <ø> (-1.83%)	⬇️
.../identity-provider/identity_provider_reconciler.go	0.00% <0.00%> (-8.60%)	⬇️
...deploy/identity-provider/identity_provider_util.go	0.00% <ø> (ø)
pkg/deploy/ingress.go	72.72% <ø> (+4.35%)	⬆️
pkg/deploy/postgres/postgres.go	36.84% <ø> (+13.43%)	⬆️
pkg/deploy/server/default_values_reconciler.go	45.54% <ø> (+0.60%)	⬆️
pkg/deploy/server/server_deployment.go	72.98% <ø> (+5.20%)	⬆️
pkg/deploy/tls/tls_secret.go	0.00% <ø> (ø)
pkg/util/util.go	18.53% <ø> (+3.89%)	⬆️
... and 4 more

---

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[tolusha]

/retest

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: tolusha

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[openshift-ci]

@tolusha: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/v8-e2e-all-namespaces-deployment	78a79cd	link	true	/test v8-e2e-all-namespaces-deployment
ci/prow/v8-multi-host-next-deployment	78a79cd	link	true	/test v8-multi-host-next-deployment
ci/prow/v8-single-host-next-deployment	78a79cd	link	true	/test v8-single-host-next-deployment
ci/prow/v9-stable-to-nightly	78a79cd	link	true	/test v9-stable-to-nightly
ci/prow/v9-multi-host-next-deployment	78a79cd	link	true	/test v9-multi-host-next-deployment
ci/prow/v9-single-host-nightly-deployment	78a79cd	link	true	/test v9-single-host-nightly-deployment
ci/prow/v9-operator-test	7f8b40d	link	true	/test v9-operator-test
ci/prow/v8-operator-test	7f8b40d	link	true	/test v8-operator-test
ci/prow/v9-devworkspace-happy-path	7f8b40d	link	true	/test v9-devworkspace-happy-path

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