Use proper SPDX license identifier (#9441)

The previously used term "3-Clause BSD License" is not properly
standarized. A common standard is SPDX, therefore "3-Clause BSD License"
is substituted with "BSD-3-Clause" which is a SPDX identifier.

`grep -rl "3-Clause BSD License" | xargs -n1 sed -i "s/3-Clause BSD
License/BSD-3-Clause/g"`

java/pom.xml

diff --git a/java/pom.xml b/java/pom.xml
index f9c2d1f..bb094a0 100644
--- a/java/pom.xml
+++ b/java/pom.xml
@@ -41,7 +41,7 @@
 
   <licenses>
     <license>
-      <name>3-Clause BSD License</name>
+      <name>BSD-3-Clause</name>
       <url>https://opensource.org/licenses/BSD-3-Clause</url>
       <distribution>repo</distribution>
     </license>