feat(SRE-8899): only support the new approach (migration 2/2)

[vmarlier]

Linear Story

We are migrating global properties outside of application helm-chart.
This is the second iteration.

The desired status is this one:

• <app>-aws-secret-application (application helm-chart)
• <app>-aws-parameter-store (application helm-chart)
• global-aws-secret (flux-config)
• global-aws-parameter-store (flux-config)

[linear]

SRE-8899 Investigate and optimize ExternalSecret consumption patterns to reduce AWS SSM Parameter Store API usage

[Copilot]

Pull request overview

This PR completes migration “2/2” by removing support for the legacy aws-secret volume approach and aligning local fixtures/runtime wiring with the new split between application-scoped and global (flux-config) config sources.

Changes:

• Removes legacy test/fixture/volumes/aws-secret/* fixtures and removes several fixtures from the application-scoped aws-parameter-store fixture set that are now treated as global.
• Updates parse-config.sh to document the 4-source layout and to stop loading $WORKDIR/aws-secret (legacy path), while continuing to load application and global sources.
• Updates docker-compose.yml to stop mounting the legacy $WORKDIR/aws-secret fixture volume.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
parse-config.sh	Drops loading of legacy $WORKDIR/aws-secret and updates inline documentation to reflect the 4 directories (app + global).
docker-compose.yml	Removes the legacy aws-secret fixture mount; keeps mounts for app-scoped and global volumes.
test/fixture/volumes/aws-secret/with_special_chars	Removes legacy secret fixture file (old approach).
test/fixture/volumes/aws-secret/infrastructure_private.terraform	Removes legacy secret fixture file (old approach).
test/fixture/volumes/aws-secret/infrastructure_openai_key	Removes legacy secret fixture file (old approach).
test/fixture/volumes/aws-secret/infrastructure_launch-darkly_key	Removes legacy secret fixture file (old approach).
test/fixture/volumes/aws-secret/infrastructure_global_launch-darkly_key	Removes legacy secret fixture file (old approach).
test/fixture/volumes/aws-secret/ignore_multiline	Removes legacy multiline fixture file (old approach).
test/fixture/volumes/aws-parameter-store/_infrastructure_msk_endpoint	Removes fixture from app-scoped parameter store set (now expected as global).
test/fixture/volumes/aws-parameter-store/_application_kerberos_redis_kerberos-authz_url	Removes fixture from app-scoped parameter store set (now expected as global).
test/fixture/volumes/aws-parameter-store/_application_kerberos_authentication_allowed_issuers	Removes fixture from app-scoped parameter store set (now expected as global).
test/fixture/volumes/aws-parameter-store/_application_global_kerberos_cache_kerberos-authz_url	Removes fixture from app-scoped parameter store set (now expected as global).

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[zbcon]

pls leave me alone