Remove fog provider support

[kathap]

Needs cloudfoundry/cloud_controller_ng#5288 to be in first.

Remove all fog references from job templates, specs and bpm config.

Complete fog removal follow-up for capi-release. All fog gems have been removed from cloud_controller_ng; this PR removes the remaining fog references from BOSH job templates and specs.

A short explanation of the proposed change:
Removes all remaining fog blobstore references from BOSH job templates, specs, and shared scripts following the fog gem removal from cloud_controller_ng.

An explanation of the use cases your change solves:
Fog blobstore support has been fully dropped. This PR ensures the BOSH release is consistent with that — no more fog properties, fog-specific nginx config, or fog+NFS setup logic. blobstore_type now defaults to storage-cli; operators using storage-cli must supply a blobstore_provider, which all cf-deployment-based environments already do.

Changes:

• Remove fog_connection from all cloud_controller_ng.yml.erb templates and job specs (all 5 jobs: cloud_controller_ng, cloud_controller_worker, cloud_controller_clock, cc_deployment_updater, blobstore_benchmark)
• Remove fog_aws_storage_options and fog_gcp_storage_options from job specs and templates
• Remove cc.log_fog_requests BOSH property and FOG_DEBUG env var from bpm.yml.erb and job specs (cloud_controller_ng, cloud_controller_worker)
• Remove legacy 'AWS' provider name from storage-cli config templates; only native 's3' is now accepted
• Remove legacy 'webdav' provider alias from storage-cli config templates; only native 'dav' is now accepted
• Update all storage-cli config specs to use native provider names (s3, dav) instead of legacy fog names
• Delete local_blobstore_downloads.conf.erb and its nginx includes — was fog-local-provider nginx config, now dead code
• Remove dead fog+NFS logic from setup_local_blobstore.sh.erb and blobstore_waiter.sh.erb
• Update bpm_spec to remove fog debug logging tests
• Update blobstore_type valid values to ['webdav', 'storage-cli'] and set the default to storage-cli (previously defaulted to the now-removed fog)
• Update blobstore_provider description to note it is required when blobstore_type is storage-cli
• Update blobstore_benchmark.mode to drop the removed fog option (default remains storage-cli)
• Removed CDN config (cdn.uri/key_pair_id/private_key) from all blobstore sections and jobs — it depended on fog/CloudFront signing, which is being removed.

Behavior change: the default blobstore_type changes from the now-removed fog to storage-cli. Deployments that relied on the implicit fog default will now use storage-cli and must set blobstore_provider (and its connection config); without a provider, CC fails at startup with No provider specified in config file. All cf-deployment-based deployments are unaffected, as they already set blobstore_type and blobstore_provider explicitly.

• Links to any other associated PRs
  Remove fog-aws and fog-core, complete fog removal cloud_controller_ng#5288
  Remove cloudfront-signer gem and dead CDN config cloud_controller_ng#5319

• I have viewed signed and have submitted the Contributor License Agreement

• I have made this pull request to the develop branch

• I have run CF Acceptance Tests on bosh lite

[jochenehret]

Tested on an AWS dev landscape, works.