Fix embedded server rebuildIndex failing with Connect Error

[vharseko]

Problem

EmbeddedDirectoryServer.rebuildIndex() always fails with:

EmbeddedDirectoryServerException: An error occurred while attempting to rebuild index ... Error code is: 1

The tool output shows what actually happens:

Password for user 'cn=Directory Manager':You have provided options for scheduling this operation as a task but options
provided for connecting to the server's tasks backend resulted in the following error: 'Connect Error'

rebuildIndex() is an offline-only operation (it requires the server to be stopped), but RebuildIndexParameters did not pass --offline to the rebuild-index tool. TaskTool runs locally only when --offline is given, so the tool went into task scheduling mode: prompted for the bind password and tried to connect to the tasks backend of the stopped server.

Found by running the slow TestNG group (excluded from CI), where EmbeddedDirectoryServerTestCase.testRebuildIndexOffline fails.

Fix

• Add --offline to RebuildIndexParameters.toCommandLineArguments().
• Move EmbeddedDirectoryServerTestCase out of the slow group into the default build (11 tests, ~1 minute). testSetupFromArchive stays in the slow group for now: it fails with "Time service not started" because the slf4j adapter still routes through the stopped main server's error log publishers — it will be enabled together with the fix for that issue.

Verification

• testRebuildIndexOffline passes (offline rebuild executes and the server restarts).
• Under the default CI group filter the class runs 11 tests, all green, ~58s.