manifests: misc improvements

[dtrifiro]

• avoid starting un-needed servers by adding RUNTIME_{GRPC,HTTP}_ENABLED env vars. This also fixes issues with the health probes reporting failures when container was started with python -m caikit.runtime.http_server or caikit.runtime.grpc_server
• add missing TRANSFORMERS_CACHE env var to transformer-container
• remove duplicated manifests

[dtrifiro]

This duplicates https://github.com/opendatahub-io/caikit-tgis-serving/blob/main/demo/kserve/custom-manifests/caikit/caikit-tgis/caikit-tgis-isvc.yaml

[dtrifiro]

This duplicates https://github.com/opendatahub-io/caikit-tgis-serving/blob/main/demo/kserve/custom-manifests/caikit/caikit-tgis/caikit-tgis-servingruntime.yaml

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: danielezonca, dtrifiro

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