[Tyagiquamar]

Description

This pull request removes the deprecated and inactive OnePerHost pod distribution value across the codebase, CRDs, templates, test requirements, and documentation as requested in #1978.

OnePerHost was deprecated dead code in pkg/apis/deployment/affinity.go: no normalizer or affinity builder handled it, and user-supplied OnePerHost values silently resolved to Unspecified without generating anti-affinity rules.

Key changes:

1. Removed PodDistributionOnePerHost constant and its entry from podDistributionTypes slice in pkg/apis/deployment/affinity.go.
2. Added normalization test coverage in pkg/apis/deployment/affinity_test.go verifying that OnePerHost passes through uncanonicalized as unrecognized.
3. Removed OnePerHost from CRD enums across deploy/operator/parts/crd.yaml, deploy/builder/templates-install-bundle/, and deploy/helm/clickhouse-operator/crds/.
4. Updated example templates and documentation (docs/custom_resource_explained.md, docs/chit-examples/104-templates.yaml, config/chi/templates.d/, deploy/helm/clickhouse-operator/values.yaml) to use standard podDistribution with ClickHouseAntiAffinity.
5. Updated requirement specs in tests/requirements/requirements.md and tests/requirements/requirements.py.

Verification

Ran unit tests inside Docker (golang:1.26-bookworm):

go test -v ./pkg/apis/deployment/...

Output:

=== RUN   TestNormalizePodDistributionType
--- PASS: TestNormalizePodDistributionType (0.00s)
=== RUN   TestNormalizePodDistributionScope
--- PASS: TestNormalizePodDistributionScope (0.00s)
=== RUN   TestNormalizePortDistributionType
--- PASS: TestNormalizePortDistributionType (0.00s)
PASS
ok  	github.com/altinity/clickhouse-operator/pkg/apis/deployment	0.017s

Fixes #1978.

[Tyagiquamar]

Hi team, following up to check if anyone has time to review this PR when convenient. Thanks!