fix(telemetry): address clang-tidy CI failures on phase10 beast test

- Add missing direct includes (contract.h, Log.h, Journal.h, uint256.h,
  suite.h, io_context.hpp, optional, stdexcept, string).
- Replace broad unit_test.h with specific unit_test/suite.h.
- Concatenate nested namespaces (xrpl::test).
- Add [[nodiscard]] to getOpenLedger/isStopping/getTrapTxID overrides.
- Make const-eligible variables const (Journal j, registry in
  disabled_construction test).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/scripts/levelization/results/ordering.txt

@@ -186,6 +186,7 @@ test.shamap > xrpl.basics
 test.shamap > xrpl.nodestore
 test.shamap > xrpl.protocol
 test.shamap > xrpl.shamap
+test.telemetry > xrpl.basics
 test.telemetry > xrpl.core
 test.telemetry > xrpld.telemetry
 test.toplevel > test.csf