feat(bigtable): add IT for querying multiple columns and rows

[mpeddada1]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 4.16667% with 46 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.03%. Comparing base (fa02b1b) to head (d6b7e19).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ogle/cloud/bigtable/tests/data_integration_test.cc	4.16%	46 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15737      +/-   ##
==========================================
- Coverage   93.05%   93.03%   -0.03%     
==========================================
  Files        2445     2445              
  Lines      225986   226034      +48     
==========================================
- Hits       210297   210284      -13     
- Misses      15689    15750      +61     

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[scotthart]

What I want to verify with this test is using StreamOf to read the rows. So let's change the for loop to look something like:

using RowType = std::tuple<std::string, std::string, std::string>;
std::vector<RowType> rows;
for (auto& row : StreamOf<RowType>(row_stream)) {
  ASSERT_STATUS_OK(row);
  rows.push_back(std::move(row));
}

EXPECT_THAT(rows, UnorderedElementsAre(RowType(), RowType("multi-column-query-row-1", "v11", "v12),
                                                                  RowType("multi-column-query-row-2", "v21", "v22")));

[scotthart]

The rest of these ASSERT/EXPECTS can be skipped after adding the above.

[mpeddada1]

Got it! This really helps in cleaning up the assertions too, thanks.