refactor(x/participationrewards/keeper): combine GetProtocolData+UnmarshalProtocolData #5260

Job	Run time
simulate quicksilver	0s
test quicksilver (amd64, linux)	2m 18s
build quicksilver (amd64, linux)	1m 41s
build quicksilver (amd64, windows)	1m 43s
test quicksilver (amd64, windows)	2m 15s
test quicksilver (darwin, arm64)	2m 19s
build quicksilver (amd64, darwin)	1m 46s
build quicksilver (darwin, arm64)	1m 55s
	13m 57s

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