Add category "thread" #1667

Job	Run time
benchmark-graph	51s
benchmark-run-once	1m 39s
test (ruby)	1m 1s
test (head)	46s
benchmark-ractor (head)	6m 49s
benchmark-default (ruby)	12m 51s
benchmark-default (truffleruby, --excludes=knucleotide,lobsters,railsbench,ruby-lsp,shipit)	12m 29s
test (truffleruby)	1m 54s
benchmark-default (head)	13m 58s
benchmark-ractor-only (head)	40s
all-tests	2s
	53m 0s

Provide feedback