Fix multi-threading aggregation feature

[v1-wizard]

This commit will fix loosing part of test results at the start of reporting during using multi-thread result aggregation feature.
I use as example realization from TestNg client: https://github.com/reportportal/agent-java-testNG/blob/develop/src/main/java/com/epam/reportportal/testng/TestNGService.java#L145

This fix should help with errors like:

[21:11:43] rp-io-1hread ERROR (SubscriptionUtils.java:97) - [96] ReportPortal Finish test item execution error
00:11:43  com.epam.reportportal.exception.ReportPortalException: Report Portal returned error
00:11:43  Status code: 404
00:11:43  Status message: Not Found
00:11:43  Error Message: Launch 'a678c4e0-c501-4e86-ba6d-a438c28e71d5' not found. Did you use correct Launch ID?
00:11:43  Error Type: LAUNCH_NOT_FOUND