Remove temporary KafkaSourceDescriptor.create function #39479

Job	Run time
Java Wordcount Direct Runner (self-hosted, ubuntu-20.04, main)	25m 1s
Java Unit Tests (macos-latest)	16m 10s
Java Wordcount Direct Runner (windows-latest)	22m 19s
Java Unit Tests (self-hosted, ubuntu-20.04, main)	26m 40s
Java Unit Tests (windows-latest)	17m 45s
Java Wordcount Direct Runner (macos-latest)	26m 33s
	2h 14m 28s

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