Threading refactor (5/7): Close ordering & shutdown hardening #49

Job	Run time
bulk-filter	28s
lint	2m 35s
windows	1m 43s
units (8)	48s
enforcer	22m 13s
changes	30s
gapic-libraries-bom	19m 6s
generation-config-check	1m 48s
units (17)	1m 21s
units (26)	1m 25s
units (21)	1m 17s
units (25)	1m 15s
units (11)	1m 17s
split-units (java-bigtable, 8)	6m 7s
split-dependencies (java-bigtable)	6m 3s
split-clirr (java-bigtable)	3m 8s
split-units (java-bigtable, 17)	9m 16s
split-units (java-bigtable, 26)	6h 0m 14s
split-units (java-bigtable, 21)	7m 36s
split-units (java-bigtable, 11)	7m 17s
split-units (java-bigtable, 25)	8m 55s
conditional-required-check	3s
	7h 44m 25s

Provide feedback