[SPARK-27346][SQL] Loosen the newline assert condition on 'examples' field in ExpressionInfo

## What changes were proposed in this pull request?

I haven't tested by myself on Windows and I am not 100% sure if this is going to cause an actual problem.

However, this one line:

https://github.com/apache/spark/blob/827383a97c11a61661440ff86ce0c3382a2a23b2/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionInfo.java#L82

made me to investigate a lot today.

Given my speculation, if Spark is built in Linux and it's executed on Windows, it looks possible for multiline strings, like,

https://github.com/apache/spark/blob/5264164a67df498b73facae207eda12ee133be7d/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala#L146-L150

to throw an exception because the newline in the binary is `\n` but `System.lineSeparator` returns `\r\n`.

I think this is not yet found because this particular codes are not released yet (see SPARK-26426).

Looks just better to loosen the condition and forget about this stuff.

This should be backported into branch-2.4 as well.

## How was this patch tested?

N/A

Closes apache#24274 from HyukjinKwon/SPARK-27346.

Authored-by: Hyukjin Kwon <[email protected]>
Signed-off-by: Hyukjin Kwon <[email protected]>

Author: HyukjinKwon

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionInfo.java

@@ -79,7 +79,7 @@ public ExpressionInfo(
         assert name != null;
         assert arguments != null;
         assert examples != null;
-        assert examples.isEmpty() || examples.startsWith(System.lineSeparator() + "    Examples:");
+        assert examples.isEmpty() || examples.contains("    Examples:");
         assert note != null;
         assert since != null;