chore: remove beta client LRO (#2497) #5379

Job	Run time
build(8) except for gapic-generator-java	3m 37s
build(8) for gapic-generator-java	9m 44s
build (11)	12m 3s
build(21) except self-service clients	11m 1s
build (17)	11m 45s
compatibility	1m 54s
lint	19s
showcase (11)	3m 58s
showcase-native	7m 24s
showcase (17)	3m 45s
gapic-generator-java-bom	1m 42s
showcase-clirr	0s
unmanaged_dependency_check	4m 15s
	1h 11m 27s

Provide feedback