[SPARK-28290][CORE][SQL] Use SslContextFactory.Server instead of SslContextFactory

[dongjoon-hyun]

What changes were proposed in this pull request?

SslContextFactory is deprecated at Jetty 9.4 and we are using 9.4.18.v20190429. This PR aims to replace it with SslContextFactory.Server.

• https://www.eclipse.org/jetty/javadoc/9.4.19.v20190610/org/eclipse/jetty/util/ssl/SslContextFactory.html
• https://www.eclipse.org/jetty/javadoc/9.3.24.v20180605/org/eclipse/jetty/util/ssl/SslContextFactory.html

[WARNING] /Users/dhyun/APACHE/spark/core/src/main/scala/org/apache/spark/SSLOptions.scala:71:
constructor SslContextFactory in class SslContextFactory is deprecated:
see corresponding Javadoc for more information.
[WARNING]       val sslContextFactory = new SslContextFactory()
[WARNING]                               ^

How was this patch tested?

Pass the Jenkins with the existing tests.

[dongjoon-hyun]

Retest this please.

[SparkQA]

Test build #107316 has finished for PR 25067 at commit 895af34.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #107317 has finished for PR 25067 at commit 895af34.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

Retest this please.

[SparkQA]

Test build #107418 has finished for PR 25067 at commit 895af34.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[tgravescs]

changes look good, +1

[dongjoon-hyun]

Thank you so much for review and approval, @tgravescs !

[dongjoon-hyun]

Merged to master.