Respect INVOKEAI_ prefix on environment variables (#4641)

## What type of PR is this? (check all applicable)
- [X] Bug Fix

## Have you discussed this change with the InvokeAI team?
- [X] Yes

## Have you updated all relevant documentation?
- [ ] Yes
- [X] N/A


## Description

Pedantic was misconfigured and was not picking up the INVOKEAI_ prefix
on environment variables. Therefore, if the system had an unrelated
environment variable such as `version`, this caused pedantic validation
errors.

## Related Tickets & Documents

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- Related Issue #
- Closes #4098 

## QA Instructions, Screenshots, Recordings

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## Added/updated tests?

- [X] Yes — regression tests run; new regression test added.

invokeai/app/services/config/invokeai_config.py

@@ -277,6 +277,7 @@ class InvokeAIAppConfig(InvokeAISettings):
 
     class Config:
         validate_assignment = True
+        env_prefix = "INVOKEAI"
 
     def parse_args(self, argv: Optional[list[str]] = None, conf: Optional[DictConfig] = None, clobber=False):
         """

tests/test_config.py

@@ -121,6 +121,12 @@ def test_env_override(patch_rootdir):
     conf.parse_args(conf=init1, argv=[])
     assert conf.max_cache_size == 20
 
+    # make sure that prefix is respected
+    del os.environ["INVOKEAI_always_use_cpu"]
+    os.environ["always_use_cpu"] = "True"
+    conf.parse_args(conf=init1, argv=[])
+    assert conf.always_use_cpu is False
+
 
 def test_root_resists_cwd(patch_rootdir):
     from invokeai.app.services.config import InvokeAIAppConfig