refactor(docker): improve Dockerfiles for authentication, graphql, subscriber, and upgrade-agents

[1107-adishjain]

Description:

This PR improves the Dockerfiles for the authentication, graphql, subscriber, and upgrade-agents services:

• Remove unnecessary RUN go env step
• Replace ADD with COPY for local context
• Remove ENV GOOS/GOARCH, pass them directly in build command
• Ensure LABEL maintainer is present in all stages

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Proposed changes

This PR refactors the Dockerfiles for core services to improve consistency, follow best practices, and reduce unnecessary steps.
No functional changes to the services themselves.

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Types of changes

What types of changes does your code introduce to Litmus? Put an x in the boxes that apply

• New feature (non-breaking change which adds functionality)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices applies)
• Refactor (code improvement with no functional change)

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Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• I have signed the commit for DCO to be passed
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

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Dependency

Please add the links to the dependent PRs that need to be merged before this (if any):

None

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Special notes for your reviewer:

N/A

[PriteshKiri]

Hey @1107-adishjain

Some checks are failing. Could you please check once?

[1107-adishjain]

Hey @1107-adishjain

Some checks are failing. Could you please check once?

Sure let me check once and fix it.

[1107-adishjain]

Hi @PriteshKiri , I have made the required fixes for the failing Docker CI checks in this PR.
Changes included:

Updated Go builder image to a patched version in authentication, graphql, and subscriber Dockerfiles.
Added runtime package update step (microdnf update + clean) in graphql and subscriber Dockerfiles to address OS-level CVEs.
Upgraded gRPC dependency to a fixed version in authentication, graphql, and subscriber modules.
Updated corresponding go.sum files after dependency updates.

Could you please re-run the checks? If everything passes, we can proceed with merge to master.