[SPARK-29218][WEBUI] Increase Show Additional Metrics checkbox widt…

…h in StagePage

### What changes were proposed in this pull request?

Modified widths of some checkboxes in StagePage.

### Why are the changes needed?

When we increase the font size of the browsers or the default font size is big, the labels of checkbox of `Show Additional Metrics` in `StagePage` are wrapped like as follows.

![before-modified1](https://user-images.githubusercontent.com/4736016/65449180-634c5e80-de75-11e9-9f27-88f4cc1313b7.png)
![before-modified2](https://user-images.githubusercontent.com/4736016/65449182-63e4f500-de75-11e9-96b8-46e92a61f40c.png)

### Does this PR introduce any user-facing change?

Yes.

### How was this patch tested?

Run the following and visit the `Stage Detail` page. Then, increase the font size.
```
$ bin/spark-shell
...
scala> spark.range(100000).groupBy("id").count.collect
```

Closes #25905 from sarutak/adjust-checkbox-width.

Authored-by: Kousuke Saruta <sarutak@oss.nttdata.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

core/src/main/resources/org/apache/spark/ui/static/stagepage.js

@@ -286,7 +286,7 @@ $(document).ready(function () {
         " Show Additional Metrics" +
         "</a></div>" +
         "<div class='container-fluid container-fluid-div' id='toggle-metrics' hidden>" +
-        "<div><input type='checkbox' class='toggle-vis' id='box-0' data-column='0'> Select All</div>" +
+        "<div id='select_all' class='select-all-checkbox-div'><input type='checkbox' class='toggle-vis' id='box-0' data-column='0'> Select All</div>" +
         "<div id='scheduler_delay' class='scheduler-delay-checkbox-div'><input type='checkbox' class='toggle-vis' id='box-11' data-column='11'> Scheduler Delay</div>" +
         "<div id='task_deserialization_time' class='task-deserialization-time-checkbox-div'><input type='checkbox' class='toggle-vis' id='box-12' data-column='12'> Task Deserialization Time</div>" +
         "<div id='shuffle_read_blocked_time' class='shuffle-read-blocked-time-checkbox-div'><input type='checkbox' class='toggle-vis' id='box-13' data-column='13'> Shuffle Read Blocked Time</div>" +

core/src/main/resources/org/apache/spark/ui/static/webui.css

@@ -263,32 +263,36 @@ a.expandbutton {
   width: 200px;
 }
 
+.select-all-div-checkbox-div {
+  width: 90px;
+}
+
 .scheduler-delay-checkbox-div {
-  width: 120px;
+  width: 130px;
 }
 
 .task-deserialization-time-checkbox-div {
-  width: 175px;
+  width: 190px;
 }
 
 .shuffle-read-blocked-time-checkbox-div {
-  width: 187px;
+  width: 200px;
 }
 
 .shuffle-remote-reads-checkbox-div {
-  width: 157px;
+  width: 170px;
 }
 
 .result-serialization-time-checkbox-div {
-  width: 171px;
+  width: 185px;
 }
 
 .getting-result-time-checkbox-div {
-  width: 141px;
+  width: 155px;
 }
 
 .peak-execution-memory-checkbox-div {
-  width: 170px;
+  width: 180px;
 }
 
 #active-tasks-table th {