git: openjdk/jdk-sandbox: jdk.javadoc/snippets: Forgot to update java.util.MapSnippets.java

[duke]

Changeset: 20e2153d
Author:    pavelrappo <pavel.rappo at gmail.com>
Date:      2021-05-04 21:24:50 +0000
URL:       https://git.openjdk.java.net/jdk-sandbox/commit/20e2153db8b9ba7a5a565d087c24cbd61bf0c915

Forgot to update java.util.MapSnippets.java

That external snippet used region identifiers, which now cause errors.

! src/java.base/share/classes/java/util/snippet-files/java/util/MapSnippets.java