Eliminate testRuntimeMigration for extensions-avro project dependency #30942

Job	Run time
Java Unit Tests (self-hosted, ubuntu-20.04, main)	18m 36s
Java Unit Tests (macos-latest)	8m 12s
Check GCP variables set	16s
Java Unit Tests (windows-latest)	13m 24s
Java Wordcount Direct Runner (self-hosted, ubuntu-20.04, main)	14m 16s
Java Wordcount Direct Runner (macos-latest)	9m 6s
Java Wordcount Direct Runner (windows-latest)	16m 57s
Java Wordcount Dataflow	0s
	1h 20m 47s

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