[SPARK-47038][BUILD] Remove shaded protobuf-java 2.6.1 dependency f…

…rom `kinesis-asl-assembly`

### What changes were proposed in this pull request?

This PR aims to remove the shaded `protobuf-java` 2.6.1 dependency from `kinesis-asl-assembly`.

### Why are the changes needed?

Technically, this is a revert of SPARK-14421.
- At that time, Apache Spark 2.0.0 distribution contains `protobuf-java-2.5.0.jar`.
  - apache#13054
- SPARK-43489 removed `protobuf-java-2.5.0.jar` from Apache Spark 3.5+ distribution.
  - apache#41153

### Does this PR introduce _any_ user-facing change?

No, but the user can inject the required protobuf-jar from application layers.

### How was this patch tested?

Pass the CIs and manual review.

**BEFORE**
```
$ build/mvn dependency:tree -pl connector/kinesis-asl-assembly -Pkinesis-asl | grep protobuf-java
...
[INFO] +- com.google.protobuf:protobuf-java:jar:2.6.1:provided
```

**AFTER**
```
$ build/mvn dependency:tree -pl connector/kinesis-asl-assembly -Pkinesis-asl | grep protobuf-java
...
[INFO] |  |  +- com.google.protobuf:protobuf-java:jar:3.25.1:provided
```

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#45096 from dongjoon-hyun/SPARK-47038.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

connector/kinesis-asl-assembly/pom.xml

@@ -59,16 +59,6 @@
       <artifactId>commons-lang</artifactId>
       <scope>provided</scope>
     </dependency>
-    <dependency>
-      <groupId>com.google.protobuf</groupId>
-      <artifactId>protobuf-java</artifactId>
-      <version>2.6.1</version>
-      <!-- 
-         We are being explicit about version here and overriding the 
-         spark default of 2.5.0 because KCL appears to have introduced 
-         a dependency on protobuf 2.6.1 somewhere between KCL 1.4.0 and 1.6.1.
-       -->
-    </dependency>
     <dependency>
       <groupId>org.glassfish.jersey.core</groupId>
       <artifactId>jersey-client</artifactId>
@@ -173,15 +163,6 @@
             <include>*:*</include>
           </includes>
         </artifactSet>
-        <relocations>
-          <relocation>
-            <pattern>com.google.protobuf</pattern>
-            <shadedPattern>kinesis.protobuf</shadedPattern>
-            <includes>
-              <include>com.google.protobuf.**</include>
-            </includes>
-          </relocation>
-        </relocations>
         <filters>
           <filter>
             <artifact>*:*</artifact>