test: step 2 refactor towards idempotency

[blaggacao]

• refactor: use cls.globalTestRecords instead of declaring test_records
  As with test: step 1 refactor towards idempotency #43610 test_records may be considered an anti-pattern if it doesn't deviate from the default behaviour. Instead, we ensure proper dependency declaration, and use self.globalTestRecords (actually: cls.globalTestRecords)

cc @ruthra-kumar @rohitwaghchaure @s-aga-r @deepeshgarg007

If we can get this to green, then this is a significant step, because it means that we have achived (or maybe only ensured, cause it already was the case) a baseline for a certain locality and isolation of tests: items inside cls.globalTestRecords are MappingProxys and therefore can't be written to. They represent the records at their time of insertion into the database. On a rerun on the CLI with the same database, they are reconstructed from sites/test_site/.test_log.jsonl instead of from an actual insert and represent the records at the time of their original insert on prior test runs.

This PR also significantly reduces the deprecation warning pressure on CLI.

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Intermediate Step Required

• feat: may copy MappingProxyType frappe#28083

AttributeError: 'mappingproxy' object has no attribute 'as_dict'

This is wonderful! It shows that the mapping proxies are working as intended. On the framework side, we want to modify at least frappe.copy_doc to work with MappingProxy, as of its widespread use in tests.

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enterClassContext / enterContext technique

All frappe.tests.classes.context_managers can be used in setUp or setUpClass with enterContext or enterClassContext. This is a relatively new unittest feature which takes a context manager and ensures the context is upheld during the entire scope of the test class / test case respecitvely.

An example of its use: c17de26

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Further Intemediate Steps Required

• fix: test record generation frappe#28102
• fix(test): Enhance test record syncing and logging functionality frappe#28094

These mainly fixed the Test Record loading for correctness. The most significant change was to load actual json records into cls.globalTestRecords instead of doc.as_dict() post db-insertion. This matches more closely the expectations that test designers had when they previously declared test_records = ....