Updated MCP server target endpoint for MCP Discovery Proxies

With the GA launch of Model Context Protocol (MCP) in Apigee, the structure of the MCP server target endpoint for MCP Discover Proxies has changed to ORG_NAME.mcp.apigee.internal.

Private preview customers using the previous format (mcp.apigee.internal) are encouraged to update their proxies to reflect the new structure. Existing endpoints using the old format will continue to work, but new endpoints will use the new structure.