revert: keep SURFACE as 'GitHub' to avoid breaking downstream telemetry pipelines

Author: cocosheng-g

action.yml

@@ -235,7 +235,7 @@ runs:
         GEMINI_CLI_VERSION: '${{ inputs.gemini_cli_version }}'
         EXTENSIONS: '${{ inputs.extensions }}'
         USE_PNPM: '${{ inputs.use_pnpm }}'
-        SURFACE: 'GH'
+        SURFACE: 'GitHub'
         GH_WORKFLOW_NAME: '${{ steps.sanitize_workflow_name.outputs.gh_workflow_name }}'
         GH_EVENT_NUMBER: '${{ inputs.github_item_number }}'
       shell: 'bash'
@@ -411,7 +411,7 @@ runs:
       env:
         GEMINI_DEBUG: '${{ fromJSON(inputs.gemini_debug || false) }}'
         GEMINI_API_KEY: '${{ inputs.gemini_api_key }}'
-        SURFACE: 'GH'
+        SURFACE: 'GitHub'
         GOOGLE_CLOUD_PROJECT: '${{ inputs.gcp_project_id }}'
         GOOGLE_CLOUD_LOCATION: '${{ inputs.gcp_location }}'
         GOOGLE_GENAI_USE_VERTEXAI: '${{ inputs.use_vertex_ai }}'