fix: remove duplicate Browserbase MCP registry entry

[Shrey Pandya (shrey150)]

Summary

• remove the duplicate legacy browserbase-mcp-server.json partner entry
• keep browserbase-mcp.json as the single canonical Browserbase registry entry

Why

Both files describe the same hosted Browserbase MCP endpoint. The canonical browserbase-mcp.json entry, added in #222, is the current submission and uses the current bearer-authentication configuration.

E2E Test Matrix

Command / flow	Observed output	Confidence / sufficiency
check-jsonschema --verbose --schemafile partners/server-schema.json partners/servers/*.json	ok -- validation done	Validates all 93 remaining partner server files against the repository schema.
Repository uniqueness checks from validate-servers.yml	All 93 server names are unique; All 103 security scheme keys are unique	Reproduces the remaining pull-request validation logic locally and confirms the deletion introduces no registry collisions.
Assert the legacy file is absent, validate the canonical file's hosted endpoint and bearer scheme with jq, then count matching hosted endpoint entries	Browserbase registry entries for hosted endpoint: 1 (canonical browserbase-mcp.json only)	Proves the requested duplicate was removed while the current hosted Browserbase entry remains intact; it does not exercise the remote MCP service because runtime behavior is unchanged.