[R] replace uses of T and F with TRUE and FALSE (#5778)

* [R-package] replace uses of T and F with TRUE and FALSE

* enable linting

* Remove skip

Co-authored-by: Philip Hyunsu Cho <chohyu01@cs.washington.edu>

demo/data/gen_autoclaims.R

@@ -14,5 +14,5 @@ data$STATE = as.factor(data$STATE)
 data$CLASS = as.factor(data$CLASS)
 data$GENDER = as.factor(data$GENDER)
 
-data.dummy <- dummy.data.frame(data, dummy.class='factor', omit.constants=T);
+data.dummy <- dummy.data.frame(data, dummy.class='factor', omit.constants=TRUE);
 write.table(data.dummy, 'autoclaims.csv', sep=',', row.names=F, col.names=F, quote=F)