fix(server): fix foreground mode exit code propagation in startup scripts

[bitflicker64]

Fix foreground mode in start-hugegraph.sh (chunk 1 of #3043)

Problem

In foreground mode (-d false), start-hugegraph.sh had a structural
bug: all post-branch logic ran unconditionally after the daemon/foreground
if/else block.

In foreground mode the script blocks at hugegraph-server.sh until Java
exits. After Java exits:

• PID="$!" captures an empty string (no background job)
• bin/pid is written with an empty string
• wait_for_startup fails immediately (empty PID, Java already dead)
• disown fails (no background jobs)
• OPEN_MONITOR fires unconditionally — even in foreground mode
• The script exits 0, losing Java's exit code entirely

This means a Java crash in foreground mode is invisible to the process
supervisor (Docker restart policy, systemd, etc.).

Fix

• Move all post-branch logic (PID="$!", pid file write, trap,
  wait_for_startup, disown, OPEN_MONITOR) inside the
  DAEMON == "true" branch where it belongs.
• In the foreground branch: background Java with &, capture $!,
  write the pid file, then wait $PID (so the script blocks while Java
  runs) and exit $? (so Java's exit code propagates out).
• Gate OPEN_MONITOR inside the daemon branch — monitor setup after a
  blocking foreground call makes no sense.

Also included

• Fix restserver.url in rest-server.properties to include the
  http:// scheme prefix (was 127.0.0.1:8080, now
  http://127.0.0.1:8080). The check_port and URL parsing in
  util.sh expect a full URL.

Tests

New script: hugegraph-server/hugegraph-dist/src/assembly/travis/test-start-hugegraph.sh

Test	Unmodified code	After fix
Test 1 — daemon mode regression	PASS	PASS
Test 2 — foreground mode blocks	PASS	PASS
Test 3 — exit code propagates (137 on SIGKILL)	FAIL	PASS
Test 4 — -m true registers cron in daemon mode	PASS	PASS

Wired into server-ci.yml after the Compile step, rocksdb backend only
(foreground mode behavior is backend-independent).

What this does NOT include

Docker entrypoint changes and runtime restart validation (kill Java
inside container → container exits → Docker restarts it) are in the
follow-up PR for chunks 4–8.

Relates to #3043 (chunk 1 of 3 startup script fixes)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 34.47%. Comparing base (b9a3dd9) to head (1f68598).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3044      +/-   ##
============================================
- Coverage     35.96%   34.47%   -1.49%     
  Complexity      338      338              
============================================
  Files           803      803              
  Lines         68053    68053              
  Branches       8907     8907              
============================================
- Hits          24472    23462    -1010     
- Misses        40955    42025    +1070     
+ Partials       2626     2566      -60     

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