Port the CLARIN S3 stack to AWS SDK v2 (decision D1)

7.6.7 rewrote S3BitStoreService from com.amazonaws (v1) to software.amazon.awssdk
(v2 CRT client). The original plan rejected that and kept v1; the user reversed it:
"if 7.6.7 is on AWS2, go to AWS2". v1 is past AWS end-of-support anyway.

The fork owns three S3 classes vanilla does not know, so this was not a file takeover:

- S3BitStoreService  = vanilla 7.6.7 + exactly three CLARIN items (47 added lines):
  getFile(Bitstream), `protected` client so the subclasses can reuse it, and a
  configurable pathStyleAccessEnabled (vanilla hardcodes forcePathStyle(true) on an
  endpoint override; keeping the property preserves the fork's v1 behaviour and keeps
  bitstore.xml valid). getFile is byte-identical to the fork's own v9 implementation
  (5e930d1) so the branches do not diverge.
- SyncS3BitStoreService     - hand-ported, including the explicit multipart path.
- S3DirectDownloadServiceImpl - presigning moved to S3Presigner, built from the same
  credentials/region/endpoint as the bitstore client.
- S3BitStoreServiceIT       - taken from 7.6.7 wholesale; the fork's copy was
  byte-identical to 7.6.5, so no CLARIN test was lost. LocalStack replaces s3mock,
  which only ever spoke v1.
- ClarinS3BitStoreServiceIT - new. The CLARIN-only paths had no test at all.
- bitstore.xml / assetstore.cfg - the merge had dropped vanilla's four new tuning keys
  (targetThroughputGbps, minPartSizeBytes, maxConcurrency, s3ChecksumAlgorithm).

Two defects the new tests caught, neither visible by reading the code:

1. v1 returned part ETags unquoted, v2 returns them quoted. The multipart checksum
   comparison would have failed on every part, and since that path logs and swallows,
   completeMultipartUpload would never run - a silent upload failure.
2. SyncS3BitStoreService.put() never closed the FileOutputStream on the local
   assetstore copy. Pre-existing, not a port regression, but it leaks a handle per
   stored bitstream and made remove() silently fail to delete the local file.

Evidence (local, this head):
- mvn test-compile -DskipTests: 13/13 modules SUCCESS
- S3BitStoreServiceIT       Tests run: 15, Failures: 0, Errors: 0
- ClarinS3BitStoreServiceIT Tests run: 6,  Failures: 0, Errors: 0
- S3DirectDownloadServiceTest Tests run: 8, Failures: 0, Errors: 0
- checkstyle 0 violations; `git grep com.amazonaws` finds nothing

s3Store is lazy-init and nothing else instantiates it, so springWiringBindsStoreProperties
loads the bean from bitstore.xml on purpose - it is the only check that the blank
maxConcurrency binds to a null Integer and that s3ChecksumAlgorithm binds to the enum.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: milanmajchrak

dspace-api/pom.xml

@@ -742,9 +742,25 @@
 
         <!-- S3 -->
         <dependency>
-            <groupId>com.amazonaws</groupId>
-            <artifactId>aws-java-sdk-s3</artifactId>
-            <version>1.12.792</version>
+            <groupId>software.amazon.awssdk</groupId>
+            <artifactId>s3</artifactId>
+            <version>2.42.40</version>
+            <exclusions>
+              <exclusion>
+                <groupId>software.amazon.awssdk</groupId>
+                <artifactId>netty-nio-client</artifactId>
+              </exclusion>
+              <exclusion>
+                <groupId>software.amazon.awssdk</groupId>
+                <artifactId>apache-client</artifactId>
+              </exclusion>
+            </exclusions>
+        </dependency>
+
+        <dependency>
+            <groupId>software.amazon.awssdk.crt</groupId>
+            <artifactId>aws-crt</artifactId>
+            <version>0.45.1</version>
         </dependency>
 
         <dependency>
@@ -860,21 +876,12 @@
             </exclusions>
         </dependency>
 
+        <!-- Replaces io.findify:s3mock, which only ever spoke AWS SDK v1. -->
         <dependency>
-            <groupId>io.findify</groupId>
-            <artifactId>s3mock_2.13</artifactId>
-            <version>0.2.6</version>
-            <scope>test</scope>
-            <exclusions>
-                <exclusion>
-                    <groupId>com.amazonawsl</groupId>
-                    <artifactId>aws-java-sdk-s3</artifactId>
-                </exclusion>
-                <exclusion>
-                    <groupId>com.amazonaws</groupId>
-                    <artifactId>aws-java-sdk-s3</artifactId>
-                </exclusion>
-            </exclusions>
+          <groupId>org.testcontainers</groupId>
+          <artifactId>testcontainers-localstack</artifactId>
+          <version>2.0.5</version>
+          <scope>test</scope>
         </dependency>
 
         <dependency>