feat(bigtable): support custom retry functions in mutate_rows shim

[daniel-sanche]

Building off of #18195 to add support for Retry object on_error and predicate. Instead of being ignored, these methods are sent through into the internal retry object

For predicate, that means retries will fail if the default predicate triggers, or the user-specified one

[gemini-code-assist]

Code Review

This pull request introduces support for legacy client shims in the mutate_rows operation by adding optional shim_predicate and shim_on_error callbacks. These callbacks are integrated into the retry tracking mechanism in both synchronous and asynchronous implementations, and corresponding unit tests have been added. The reviewer suggests defensively using getattr when accessing attributes on the retry and DEFAULT_RETRY objects to prevent potential AttributeErrors if duck-typed or custom objects are passed.

[gemini-code-assist]

To prevent potential AttributeErrors when retry or DEFAULT_RETRY are duck-typed or custom objects that do not implement all attributes (such as deadline or _predicate), we should use getattr defensively for all attribute accesses on these objects.

Suggested change

	if retry is None or getattr(retry, "deadline", None) == 0:
	operation_timeout = TABLE_DEFAULT.MUTATE_ROWS
	retryable_errors = []
	else:
	operation_timeout = retry.deadline
	operation_timeout = (
	retry.deadline
	if retry.deadline is not None
	else TABLE_DEFAULT.MUTATE_ROWS
	)
	if (
	getattr(retry, "_predicate", None) is not None
	and retry._predicate is not DEFAULT_RETRY._predicate
	):
	shim_predicate = retry._predicate
	if retry is None or getattr(retry, "deadline", None) == 0:
	operation_timeout = TABLE_DEFAULT.MUTATE_ROWS
	retryable_errors = []
	else:
	deadline = getattr(retry, "deadline", None)
	operation_timeout = (
	deadline
	if deadline is not None
	else TABLE_DEFAULT.MUTATE_ROWS
	)
	retry_predicate = getattr(retry, "_predicate", None)
	default_predicate = getattr(DEFAULT_RETRY, "_predicate", None)
	if retry_predicate is not None and retry_predicate is not default_predicate:
	shim_predicate = retry_predicate

[daniel-sanche]

Actually, doing more research, it looks like on_error and predicate were never truly supported in the client, so we can avoid this change