[hotfix][runtime] Fix concurrency issue in callback runner of async s… #256

Job	Run time
Default (Java 8) / Compile	47m 0s
Pre-compile Checks / Basic QA	10m 31s
Default (Java 8) / E2E (group 1)	2h 12m 5s
Default (Java 8) / Test packaging/licensing	37m 32s
Default (Java 8) / E2E (group 2)	2h 31m 37s
Default (Java 8) / Test (module: core)	31m 4s
Default (Java 8) / Test (module: python)	31m 48s
Default (Java 8) / Test (module: table)	39m 5s
Default (Java 8) / Test (module: connect)	20m 51s
Default (Java 8) / Test (module: tests)	36m 45s
Default (Java 8) / Test (module: misc)	41m 44s
	9h 40m 2s

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