Fix misleading error on project import quota violation

Previously, when a project import failed during the GitCloneStep, the
error handling logic assumed that all `ResourceConflictException`s
indicated the repository already existed. This led to incorrect error
messages being shown to users, even when the actual cause was unrelated.

This patch removes the special handling for `ResourceConflictException`
and instead exposes the full underlying message from the
`RestApiException`. As a result, users now receive accurate feedback,
for example, when import fails due to exceeding the `maxProjects` quota
in a namespace.

Improves user experience by providing correct diagnostics for import
failures, aiding in quicker debugging and resolution.

Bug: Issue 445765274
Change-Id: I7ab32c23140288b3c259d4b8e5fcb3135f14ce7c

github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/GitCloneStep.java

diff --git a/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/GitCloneStep.java b/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/GitCloneStep.java
index 9d09f51..d2b589f 100644
--- a/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/GitCloneStep.java
+++ b/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/GitCloneStep.java
@@ -21,7 +21,6 @@
 import com.google.gerrit.extensions.api.projects.ProjectInput;
 import com.google.gerrit.extensions.events.ProjectDeletedListener;
 import com.google.gerrit.extensions.registration.DynamicSet;
-import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountState;
@@ -114,10 +113,9 @@
       pi.parent = config.getBaseProject(ghRepository.isPrivate());
       pi.branches = Stream.ofNullable(ghRepository.getDefaultBranch()).collect(toList());
       gerritApi.projects().create(pi).get();
-    } catch (ResourceConflictException e) {
-      throw new GitDestinationAlreadyExistsException(projectName);
     } catch (RestApiException e) {
-      throw new GitException("Unable to create repository " + projectName, e);
+      throw new GitException(
+          "Unable to create repository " + projectName + ":" + e.getMessage(), e);
     }
   }