Add support for collection export

[jfrancoa]

What's being changed

Adds Helm chart support for Weaviate's collection export feature, introduced in weaviate/weaviate#10958.

values.yaml — new top-level collectionExport section (mirrors the pattern of backups and offload):

• collectionExport.enabled — gates the feature; when true, injects EXPORT_ENABLED=true into the pod
• collectionExport.envconfig.EXPORT_DEFAULT_BUCKET — required bucket name (defaults to weaviate-export); the bucket must exist before enabling, otherwise exports will fail
• collectionExport.envconfig.EXPORT_DEFAULT_PATH — optional path prefix inside the bucket (commented out, defaults to empty)
• collectionExport.envconfig.EXPORT_PARALLELISM — optional number of concurrent scan workers per export (commented out, defaults to 0 = GOMAXPROCS at runtime)

templates/weaviateStatefulset.yaml — renders the env vars when collectionExport.enabled=true; all other collectionExport.envconfig keys are forwarded as-is, so future env vars require no template changes.

.cicd/test.sh — test cases covering:

• EXPORT_ENABLED and EXPORT_DEFAULT_BUCKET are absent by default
• Both are injected when the feature is enabled
• Custom bucket name overrides the default
• EXPORT_DEFAULT_PATH and EXPORT_PARALLELISM are absent by default but can be set via envconfig
• Pass the namespace in certain tests, as otherwise the CI will start failing once the github runners upgrade from Helm v3 to v4.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Secrets	0   0   0   0	View in Orca

[antas-marcin]

by default we will be setting EXPORT_DEFAULT_PATH empty? shouldn't this be commented as EXPORT_PARALLELISM?

[jfrancoa]

I think the env var is required now. I did try enabling the feature the other day without the env var set and it was faling with this error.
That's what Dirk mentioned by saying that the env var is now required, but it can be default to "". If we don't pass it like that, the cluster will error and won't enable the feature.