refactor(x/participationrewards/keeper): combine GetProtocolData+UnmarshalProtocolData #5282

Job	Run time
build quicksilver (amd64, linux)	1m 46s
build quicksilver (amd64, windows)	1m 50s
build quicksilver (amd64, darwin)	1m 48s
build quicksilver (darwin, arm64)	1m 52s
test quicksilver (amd64, linux)	13m 32s
test quicksilver (amd64, windows)	13m 4s
simulate quicksilver	0s
test quicksilver (darwin, arm64)	13m 15s
	47m 7s

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