Create shared schemas collector for DBM integrations

[sethsamuel]

What does this PR do?

Adds a shared schema collector for the DBM integrations (Postgres, MySQL, SQLServer).

Motivation

This class centralizes shared logic around iteration, buffering, submission, etc. Individual integrations will implement subclasses that handle actual data retrieval and mapping. See #21501 for the Postgres implementation.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
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[datadog-official]

⚠️ Tests

⚠️ Warnings

❄️ 1 New flaky test detected

test_statement_metrics_and_plans[master-EXEC multiQueryProc-expected_queries_patterns1-param_groups1-5-False-True-True-False-multiqueryproc] from test_statements.py (Datadog)

missing expected matching rows
assert 1 == 2
 +  where 1 = len([{'dd_commands': ['SELECT'], 'dd_comments': [], 'dd_tables': ['ϑings'], 'execution_count': 5, ...}])
 +  and   2 = len(["select @total = @total \\+ count\\(\\*\\) from sys\\.databases where name like '%_'", "select @total = @total \\+ count\\(\\*\\) from sys\\.sysobjects where type = 'U'"])

ℹ️ Info

🧪 All tests passed

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 2a65b0a | Docs | Was this helpful? Give us feedback!}

[codecov]

Codecov Report

❌ Patch coverage is 89.36170% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.12%. Comparing base (74c7edc) to head (2a65b0a).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

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[chatgpt-codex-connector]

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[eric-weaver]

Pymysql and psycopg cursors are iterable. I suspect the same for SqlServer drivers. We should be able to iterate the cursor directly an avoid the need for _get_next(). Did you try something like the following

Suggested change

	with self._get_cursor(database_name) as cursor:
	# Get the next row from the cursor
	next = self._get_next(cursor)
	while next:
	with self._get_cursor(database_name) as cursor:
	for next in cursor:

[eric-weaver]

Worth including some stats in here? Such as how many databases/tables collected / time passed?

[eric-weaver]

Suggested change

	self._log.warning("database has no name %v", database)
	self._log.warning("database has no name %s", database)

Strings should use %s

[sethsamuel]

This is the database object

[eric-weaver]

Suggested change

	def _get_cursor(self, database):
	def _get_cursor(self, database) -> AbstractContextManager[Any]:

I think we can type this as requiring a context manager using from contextlib import AbstractContextManager