CCM-18535: new proxygen mtls namespace

[francisco-videira-nhs]

Description

Context

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

DT3-Specific Checklist

• If I have added a new resource (SQS, Lambda, Gateway, DDB table, etc), I have created the appropriate alarms

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Sensitive Information Declaration

To ensure the utmost confidentiality and protect your and others privacy, we kindly ask you to NOT including PII (Personal Identifiable Information) / PID (Personal Identifiable Data) or any other sensitive data in this PR (Pull Request) and the codebase changes. We will remove any PR that do contain any sensitive information. We really appreciate your cooperation in this matter.

• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[Copilot]

Pull request overview

Renames the mTLS secret references for the Proxygen deployments to use the consistent nhs-notify-supplier-* namespace per environment, and removes a now-redundant block from the build-proxies GitHub Action that previously set INSTANCE, TARGET, SANDBOX_TAG, and MTLS_NAME env vars (this logic has moved to the internal proxy-deploy workflow).

Changes:

• Updates mTLS secret names in ref, int, internal-dev, and internal-dev-pr target specs to the new namespaced convention.
• Uses a prNNN placeholder in the internal-dev-pr target that is dynamically replaced by the internal proxy-deploy workflow.
• Removes the per-PR / non-PR setup block (INSTANCE, TARGET, SANDBOX_TAG, MTLS_NAME) from .github/actions/build-proxies/action.yml.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
specification/api/components/environments/ref/target.yml	Renames mTLS secret to nhs-notify-supplier-mtls-ref.
specification/api/components/environments/int/target.yml	Renames mTLS secret to nhs-notify-supplier-mtls-int.
specification/api/components/environments/internal-dev/target.yml	Renames mTLS secret to nhs-notify-supplier-mtls-internal-dev.
specification/api/components/environments/internal-dev-pr/target.yml	Uses prNNN placeholder, replaced at deploy time by the internal proxy-deploy workflow.
.github/actions/build-proxies/action.yml	Removes obsolete PR/non-PR env-var block now handled by the internal repo workflow.