[MINOR][DOCS] Remove extraneous whitespace from SQL tuning page

docs/sql-performance-tuning.md

@@ -176,48 +176,33 @@ Note that there is no guarantee that Spark will choose the join strategy specifi
 a specific strategy may not support all join types.
 
 <div class="codetabs">
-
-<div data-lang="python"  markdown="1">
-
-{% highlight python %}
+<div data-lang="python" markdown="1">
+```python
 spark.table("src").join(spark.table("records").hint("broadcast"), "key").show()
-{% endhighlight %}
-
+```
 </div>
-
-<div data-lang="scala"  markdown="1">
-
-{% highlight scala %}
+<div data-lang="scala" markdown="1">
+```scala
 spark.table("src").join(spark.table("records").hint("broadcast"), "key").show()
-{% endhighlight %}
-
+```
 </div>
-
-<div data-lang="java"  markdown="1">
-
-{% highlight java %}
+<div data-lang="java" markdown="1">
+```java
 spark.table("src").join(spark.table("records").hint("broadcast"), "key").show();
-{% endhighlight %}
-
+```
 </div>
-
-<div data-lang="r"  markdown="1">
-
-{% highlight r %}
+<div data-lang="r" markdown="1">
+```r
 src <- sql("SELECT * FROM src")
 records <- sql("SELECT * FROM records")
 head(join(src, hint(records, "broadcast"), src$key == records$key))
-{% endhighlight %}
-
+```
 </div>
-
-<div data-lang="SQL"  markdown="1">
-
-{% highlight sql %}
+<div data-lang="SQL" markdown="1">
+```sql
 -- We accept BROADCAST, BROADCASTJOIN and MAPJOIN for broadcast hint
 SELECT /*+ BROADCAST(r) */ * FROM records r JOIN src s ON r.key = s.key
-{% endhighlight %}
-
+```
 </div>
 </div>