fix: finish benchmarks migration and remove init.sh from benchmark folders

[Imod7]

Description

• Migrated the remaining camelCase benchmark directories to snake_case Lua scripts using the util API
• Removed all init.sh files from every benchmark folder
• Refactored scripts/runBenchmarks.ts to call wrk directly.
• Updated all paths in scripts/benchmarkConfig.ts so every endpoint resolves to an existing directory.
• Added validation to .github/workflows/benchmark.yml

Reason

The benchmark workflow has been failing on every push to master since #1917 + #1928. The new util.request(handler, path) API expects a function, but the camelCase scripts still passed a table > "attempt to call a table value" > empty benchmarks.txt > 0 entry JSON > github-action-benchmark errors out with No benchmark result was found.

Test plan

• npx tsc --project scripts/tsconfig.json --noEmit
• yarn build:scripts
• Every entry in benchmarkConfig.ts resolves to benchmarks/<dir>/<dir>.lua (30/30)
• yarn bench --endpoint "/accounts/{accountId}/validate" --time 30s --ws-url wss://rpc.polkadot.io generates non-empty benchmarks.txt containing Avg RequestTime(Latency): 0.50ms
• generate_benchmark_result.sh on that output produces a 1-entry valid JSON