chore: remove legacy `rnpm` config #8045

Job	Run time
diff_check / diff_check	8s
cancel-previous-workflow	5s
metrics (legacy, ios)	10m 40s
Build RN 0.65.3 legacy hermes android production no	4m 46s
metrics (legacy, android)	4m 29s
Build RN 0.65.3 legacy jsc android production no	4m 47s
metrics (new, ios)	6m 49s
Build RN 0.65.3 legacy hermes ios production no	15m 29s
metrics (new, android)	13m 50s
Build RN 0.65.3 legacy jsc ios production no	16m 16s
Build RN 0.73.2 legacy hermes android production no	4m 55s
Build RN 0.73.2 legacy hermes ios production no	16m 27s
Build RN 0.73.2 legacy hermes ios production static	13m 42s
Build RN 0.73.2 legacy hermes ios production dynamic	15m 51s
Build RN 0.73.2 new hermes android production no	5m 21s
Build RN 0.73.2 new hermes ios production no	19m 28s
Build RN 0.73.2 new hermes ios production static	18m 31s
Test RN 0.65.3 legacy jsc android production no	4m 31s
Test RN 0.65.3 legacy jsc ios production no	12m 0s
Test RN 0.73.2 legacy hermes android production no	3m 22s
Test RN 0.73.2 legacy hermes ios production no	12m 42s
Test RN 0.73.2 new hermes android production no	4m 5s
	3h 28m 14s

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