kernelci-pipeline: Remove patch file for staging TOML

The pipeline running on staging instance used to use `staging.kernelci.org.toml` file for the configurations. The patch file [`kernelci-deploy/patches/kernelci-pipeline/staging.kernelci.org/0001-STAGING-config-staging.kernelci.org.toml-add-file-fo.patch`](https://github.com/kernelci/kernelci-deploy/blob/main/patches/kernelci-pipeline/staging.kernelci.org/0001-STAGING-config-staging.kernelci.org.toml-add-file-fo.patch) was being used to maintain the TOML file.
We are using `staging.kernelci.org.secrets.toml` atm on the staging instance. Hence, we can consider removing the patch file and writing a new one for the currently used TOML file or think about other ways to maintain it.

Start by inspecting kernelci-deploy/patches/kernelci-pipeline/staging.kernelci.org/0001-STAGING-config-staging.kernelci.org.toml-add-file-fo.patch and compare it with the staging.kernelci.org.secrets.toml configuration mentioned in the issue. Determine whether the obsolete patch should be removed or replaced, and consider the repository's existing deployment configuration approach. Done means the staging pipeline is maintained by the current configuration without the outdated patch.

Written by the indexing model from the issue text.