Refactored flaky tests in vertex-redis-client-3.9 to retry connection rather than fail with NPE#9390

AlexeyKuznetsov-DD merged 3 commits intomasterDataDog/dd-trace-java:masterfrom

alexeyk/vertex-redis-flaky-npeDataDog/dd-trace-java:alexeyk/vertex-redis-flaky-npeCopy head branch name to clipboard