fix(telemetry): resolve phase-7 clang-tidy findings

- OTelCollector::formatName made static (no member state); braces added;
  <cctype> added for std::tolower.
- Telemetry.cpp getMeter(): braces around single-statement if.
- GetMeter.cpp: drop unused <opentelemetry/metrics/meter.h> and
  sync_instruments.h; add <xrpl/beast/utility/Journal.h> and <memory>;
  make sdkProvider const.
- ValidationTracker.h: add <cstddef> for std::size_t.
- detail/ValidationTracker.cpp: use std::views::reverse range-based loop;
  add <ranges>.
- test ValidationTracker.cpp: use auto for cast result.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/libxrpl/telemetry/Telemetry.cpp

@@ -535,8 +535,10 @@ public:
     getMeter(std::string_view name = kMeterName) override
     {
         if (!meterProvider_)
+        {
             return metrics_api::Provider::GetMeterProvider()->GetMeter(
                 std::string(name), std::string(kMeterVersion));
+        }
         return meterProvider_->GetMeter(std::string(name), std::string(kMeterVersion));
     }