Stackdriver: Make service list searchable (#20989)

* remove non-searchable option

* fix unit test

Signed-off-by: Kevin Labesse <kevin@labesse.me>

* fix unit test

public/app/plugins/datasource/stackdriver/components/Metrics.tsx

@@ -162,7 +162,6 @@ export class Metrics extends React.Component<Props, State> {
               onChange={this.onServiceChange}
               value={service}
               options={services}
-              isSearchable={false}
               placeholder="Select Services"
               className="width-15"
             />

public/app/plugins/datasource/stackdriver/components/__snapshots__/QueryEditor.test.tsx.snap

@@ -31,17 +31,62 @@ Array [
               >
                 Select Services
               </div>
-              <input
-                className="css-14uuagi"
-                disabled={false}
-                id="react-select-2-input"
-                onBlur={[Function]}
-                onChange={[Function]}
-                onFocus={[Function]}
-                readOnly={true}
-                tabIndex="0"
-                value=""
-              />
+              <div
+                className="css-0"
+              >
+                <div
+                  className="gf-form-select-box__input"
+                  style={
+                    Object {
+                      "display": "inline-block",
+                    }
+                  }
+                >
+                  <input
+                    aria-autocomplete="list"
+                    autoCapitalize="none"
+                    autoComplete="off"
+                    autoCorrect="off"
+                    disabled={false}
+                    id="react-select-2-input"
+                    onBlur={[Function]}
+                    onChange={[Function]}
+                    onFocus={[Function]}
+                    spellCheck="false"
+                    style={
+                      Object {
+                        "background": 0,
+                        "border": 0,
+                        "boxSizing": "content-box",
+                        "color": "inherit",
+                        "fontSize": "inherit",
+                        "opacity": 1,
+                        "outline": 0,
+                        "padding": 0,
+                        "width": "1px",
+                      }
+                    }
+                    tabIndex="0"
+                    type="text"
+                    value=""
+                  />
+                  <div
+                    style={
+                      Object {
+                        "height": 0,
+                        "left": 0,
+                        "overflow": "scroll",
+                        "position": "absolute",
+                        "top": 0,
+                        "visibility": "hidden",
+                        "whiteSpace": "pre",
+                      }
+                    }
+                  >
+                    
+                  </div>
+                </div>
+              </div>
             </div>
             <div
               className="css-0 gf-form-select-box__indicators"