Legacy RNG global generator becomes stale across server restart, causing UnknownSymbolError in seed()

[ajpotts]

Problem:
CI fails with:
RuntimeError: Error executing command delGenerator: UnknownSymbolError ... unknown symbol

This occurs when ak.random.seed() attempts to delete the legacy global RNG generator using a symbol name that no longer exists on the server. The client-side global (theGenerator) persists across Arkouda server restarts / reconnects, but the server symbol table does not.

Trigger:
Recent changes to test ordering (adding random_legacy_alignment tests) expose this bug by causing ak.random.seed() to be called after a server reset.

Expected Behavior:
Calling ak.random.seed() should be robust even if a previous global generator was already deleted or lost due to a server restart.

Actual Behavior:
ak.random.seed() calls theGenerator.destructor(), which unconditionally sends delGenerator for a stale symbol name, causing CI failure.

Root Cause:
Legacy RNG uses a module-level global generator handle that is not reset when the Arkouda server restarts or the client reconnects.

Proposed Fixes (preferred order):

1. Make ak.random.seed() tolerant of missing generators by ignoring UnknownSymbolError during destructor.
2. Reset legacy RNG global state on Arkouda connect/disconnect.
3. (Less ideal) Test-side mitigation to enforce consistent server lifecycle.

Files Involved:

• arkouda/numpy/random/legacy.py
• arkouda/numpy/random/generator.py
• tests/numpy/random_test.py

Acceptance Criteria:

• ak.random.seed() no longer fails after server restarts.
• CI passes regardless of test ordering.
• No regression in RNG reproducibility tests.