test(spelling): fix spelling/typo in string

public/app/plugins/datasource/opentsdb/specs/datasource-specs.ts

@@ -36,14 +36,14 @@ describe('opentsdb', function() {
       expect(requestOptions.params.q).to.be('pew');
     });
 
-    it('tag_names(cpu) should generate looku  query', function() {
+    it('tag_names(cpu) should generate lookup query', function() {
       ctx.ds.metricFindQuery('tag_names(cpu)').then(function(data) { results = data; });
       ctx.$rootScope.$apply();
       expect(requestOptions.url).to.be('/api/search/lookup');
       expect(requestOptions.params.m).to.be('cpu');
     });
 
-    it('tag_values(cpu, test) should generate looku  query', function() {
+    it('tag_values(cpu, test) should generate lookup query', function() {
       ctx.ds.metricFindQuery('tag_values(cpu, hostname)').then(function(data) { results = data; });
       ctx.$rootScope.$apply();
       expect(requestOptions.url).to.be('/api/search/lookup');