chore: remove Go components

[lucarlig]

Summary

• Remove Go sources, templates, docs, CI/tooling, vulnerability/license scanning, and Go-specific server assets from the repository.
• Keep the existing fast-time public surface while backing it with the Rust fast-time-server from the underlying PR.
• Preserve Helm mcpFastTimeServer, ingress, service, notes, and registration knobs, now pointing at the Rust Streamable HTTP /mcp endpoint.
• Remove the duplicate testing.fastTest* chart path and normalize tests, examples, wrapper scripts, load/performance configs, and plugin examples to fast-time naming.
• Remove leftover Go-backed A2A echo, benchmark-server, and slow-time chart/compose/test surfaces that no longer have an implementation after the Go tree is deleted.
• Keep generic A2A runtime, gateway benchmark/load tooling, and Rust fast-time virtual-server benchmark flows intact.

Verification

• cargo fmt --check && cargo test in mcp-servers/rust/fast-time-server
• cargo test -p mcp_stdio_wrapper --bin wrapper_integration --features integration-test
• .venv/bin/python -m pytest tests/unit/test_docker_scan_workflow.py tests/unit/mcpgateway/services/test_prompt_service.py -q
• .venv/bin/python -m pytest tests/unit/test_docker_scan_workflow.py -q
• .venv/bin/python -m py_compile scripts/license_checker.py tests/performance/utils/generate_docker_compose.py tests/loadtest/locustfile_echo_delay.py
• .venv/bin/python -m py_compile tests/loadtest/locustfile.py tests/performance/utils/generate_docker_compose.py scripts/license_checker.py
• structured JSON/YAML/TOML/config parse for Helm values, OCP/minikube profiles, catalog, schema, license policy, and performance config
• helm lint charts/mcp-stack
• helm template smoke charts/mcp-stack --set testing.enabled=true --set mcpFastTimeServer.enabled=true
• helm template smoke charts/mcp-stack -f charts/mcp-stack/values-minikube.yaml
• helm template smoke charts/mcp-stack -f charts/mcp-stack/profiles/ocp/values-pgo.yaml
• docker compose ... config for default, debug, performance, verbose logging, embedded overlay, and Langfuse overlay
• git diff --check