Remove runtime refresh of client telemetry configuration

Client telemetry has no supported runtime configuration API. Repeatedly reading environment variables and fallback files adds work and allows Python settings to diverge from cppTango's cached settings.

• Remove refresh_from_env and its client and factory call sites
• Use import-time endpoints as factory defaults, allowing overrides
• Initialize test configuration through a module reload fixture
• Resolve endpoint classes through the reloaded telemetry module
• Verify later environment changes leave client settings unchanged
• Document import-time configuration and restart requirements
• Update, and simplify tests, where possible

Co-authored-by: Codex codex@openai.com