[VictoriaMetrics] Consolidate systemd storage paths on LXC 240

[letwir]

Depends on completion of all VictoriaMetrics imports.

Target layout:

• binaries: /opt/victoriametrics/bin
• TSDB: /opt/victoriametrics/db/tsdb
• logs DB: /opt/victoriametrics/db/log

Tasks:

• Move the active TSDB safely.
• Update and enable the systemd unit.
• Verify restart and boot-time startup.