Fix description of fields in the pipeline

The description of fields in the upgrade_mcp_pipeline is confusing
since "release/TARGET_MCP_VERSION" works only for real releases,
MUs should be referenced without the "release" keyword.

Closes-Bug: PROD-35243
Change-Id: Ib66f4e8b11381a8b9117d69659ef44a68ba4df73
1 file changed