The s3-service-name.patch renamed the S3 Service to <name>-s3
(seaweedfs-s3), but several consumers still resolved it through
componentName -> <fullname>-s3. name and fullname only coincide when the
release name equals the chart name; the shipped release is
seaweedfs-system, so they pointed at seaweedfs-system-s3 while the real
service stayed seaweedfs-s3:

- the S3 ingress backend and the iceberg ingress backend, which left
  ingress-nginx returning 503 on the external S3 endpoint.

The COSI provisioner in-cluster ENDPOINT was wrong on the same axis and
also on the port. Both the s3-gateway branch and the filer-S3 branch
rendered a portless URL that defaults to 443, while the s3 service only
listens on the S3 port (8333); the filer branch additionally targeted
the filer service, which serves no S3. Both in-cluster branches now
resolve seaweedfs-s3 on the configured S3 port.

The default path (s3.ingress.enabled=true) is repaired by the ingress
fix; the COSI in-cluster paths are latent until an operator disables the
ingress. Resolve every consumer through the same name helper the Service
uses, and pin the contract with unittests rendered under the production
release name so the mismatch cannot recur.

Assisted-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>
(cherry picked from commit 8a14de9)