Use Boolean.valueOf to test strings

The check

if("true".equals(locked.toLowerCase()))

in

https://github.com/openmrs/openmrs-core/blob/master/api/src/main/java/org/openmrs/api/impl/PersonServiceImpl.java#L949

can be replaced by

if(Boolean.valueOf(locked))

Boolean.valueOf(String)

since Boolean.valueOf(String) returns true if the string argument is not null and is equal, ignoring case, to the string "true" and otherwise false

all occurences as pointed out by sonar issue should be replaced
https://ci.openmrs.org/sonar/drilldown/issues/1865?&rule=squid%3AS1157&rule_sev=MAJOR