Refine `parserStatement` grammar in P4 parser #5858

Job	Run time
test-ubuntu24	29m 55s
test-ubuntu22 (Unity OFF, GTest OFF)	48m 28s
test-ubuntu22 (Unity ON, GTest ON)	27m 6s
test-ubuntu22-tofino	42m 52s
	2h 28m 21s

Provide feedback