test(spanner): handle Node 18 prototype equality in PartialResultStream row assertions

[sakthivelmanii]

Node 18's assert.deepStrictEqual strictly enforces prototype equality (Object.getPrototypeOf(a) === Object.getPrototypeOf(b)), which causes assertions comparing RowImpl (an Array subclass with constructor: Array) against plain Array literals (EXPECTED_ROW) to fail with "Values have same structure but are not reference-equal".

Add a Node major version check in PartialResultStream row emission unit tests to spread row into a standard Array on Node < 20 while asserting row directly on Node 20+, keeping tests green across all supported Node versions without altering the RowImpl performance optimizations.

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Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Code Review

This pull request updates tests in handwritten/spanner/test/partial-result-stream.ts to handle Node 18's strict prototype equality checks in assert.deepStrictEqual by conditionally spreading row based on the Node version. The reviewer suggests simplifying this logic by always spreading row into a plain array, which works consistently across all Node versions and eliminates the need for version-specific branching.

[gemini-code-assist]

Instead of parsing process.versions.node and branching based on the Node version, we can simplify the test by always spreading row into a plain array ([...row]). This works consistently across all Node versions, avoids version-specific logic, and makes the test code much cleaner and easier to maintain.

Suggested change

	// Node 18's assert.deepStrictEqual strictly requires prototype equality,
	// which fails when comparing RowImpl (an Array subclass) with a plain Array literal.
	// Node 20+ relaxed this for Array subclasses with constructor = Array.
	if (parseInt(process.versions.node.split('.')[0], 10) < 20) {
	assert.deepStrictEqual([...row], EXPECTED_ROW);
	} else {
	assert.deepStrictEqual(row, EXPECTED_ROW);
	}
	// Spread row into a plain array to avoid prototype equality failures in Node 18's assert.deepStrictEqual.
	assert.deepStrictEqual([...row], EXPECTED_ROW);

[sakthivelmanii]

We want to get rid of this, when we move to Node 22.