fix(trace-exporter): revert accidental changes.

experimental/packages/exporter-trace-otlp-http/test/common/CollectorTraceExporter.test.ts

@@ -18,7 +18,7 @@ import { ExportResultCode } from '@opentelemetry/core';
 import { ReadableSpan } from '@opentelemetry/sdk-trace-base';
 import * as assert from 'assert';
 import * as sinon from 'sinon';
-import { OTLPExporterBase } from '../../src';
+import { OTLPExporterBase } from '../../src/OTLPExporterBase';
 import { OTLPExporterConfigBase } from '../../src/types';
 import { mockedReadableSpan } from '../traceHelper';
 import * as otlpTypes from '../../src/types';