Remove unused Docker-SDK port detection in tasks.py

[Valyrian-Code]

Fixes #627.

Background

e2c6309 removed the top-level import docker from src/tasks.py (and moved _docker_host_ip() off the Docker SDK), but _container_exposed_port() still called docker.from_env(...). With no import, that call raised NameError, which the function's try/except swallowed — printing a traceback and falling back to "80" — on every start where GEONODE_LB_PORT is unset.

As discussed in #627 (thanks @mattiagiupponi), the public port is sourced from GEONODE_LB_PORT, so the Docker-API detection isn't needed.

Change

• Remove _container_exposed_port() entirely.
• Simplify _geonode_public_port() to rely on GEONODE_LB_PORT.
• Drop the now-unused import re (its only use was inside the removed function).

Behavior

Equivalent to before. Previously, when GEONODE_LB_PORT was unset, _container_exposed_port() returned "80", which update() then normalized to None (via if ... or pub_port == "80": pub_port = None). The simplified function returns None directly for unset / "80" / "443", and the explicit value otherwise — same end result.

Verification

• python -m py_compile src/tasks.py passes.
• No remaining references to docker., re., or _container_exposed_port in the module.