fix the problem that some hive databases do not display.

for example, there are "a", "b", "c", "default", "e", "f"  as hive databases.
in this case, "e" and "f" do not display.

I think that it is correct to use splice(index, howmany).

for example,

var dbnamelist = ["a", "b", "c", "default", "e", "f"];
var len = dbnamelist.length;
for (var i = 0 ; i < len ; i++) {
  if (dbnamelist[i] === "default") {
    dbnamelist.splice(i);
    break;
  }
}
dbnamelist.unshift("default");
//[ 'default', 'a', 'b', 'c']

var dbnamelist = ["a", "b", "c", "default", "e", "f"];
var len = dbnamelist.length;
for (var i = 0 ; i < len ; i++) {
  if (dbnamelist[i] === "default") {
    dbnamelist.splice(i, 1);
    break;
  }
}
dbnamelist.unshift("default");
//[ 'default', 'a', 'b', 'c', 'e', 'f' ]