message: feat(tracing): Add GB unit to device memory tag value
  Since tag values are always strings, it'll be useful to attach units to the `deviceMemory` tag. Since `navigator.deviceMemory` are approximate in gigabytes, we can suffix the tag value with " GB".
  Reference:
diff: @@ -211,7 +211,7 @@ export class MetricsInstrumentation {
  }
  if (isMeasurementValue(navigator.deviceMemory)) {
  - transaction.setTag('deviceMemory', String(navigator.deviceMemory));
  + transaction.setTag('deviceMemory', `${navigator.deviceMemory} GB`);
  }
  if (isMeasurementValue(navigator.hardwareConcurrency)) {
  