Remove MCP servers column from generated agents README (#4171)

The README build fetched the live GitHub MCP registry to decide whether to
link server names, which made output nondeterministic (e.g. Apify) and
caused the validate-readme check to fail intermittently.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: aaronpowell