refactor(client): Cosmetic cleanup in client.h
refactor(client): Cosmetic cleanup in client.h

StalderT/open62541,StalderT/open62541,StalderT/open62541,JGrothoff/open62541,open62541/open62541,JGrothoff/open62541,open62541/open62541,JGrothoff/open62541,StalderT/open62541,JGrothoff/open62541,jpfr/open62541,jpfr/open62541,open62541/open62541,jpfr/open62541,jpfr/open62541,open62541/open62541