Sometimes in CI the columnar_memory test was using slightly more memory
than expected.
```diff
SELECT CASE WHEN 1.0 * TopMemoryContext / :top_post BETWEEN 0.98 AND 1.02 THEN 1 ELSE 1.0 * TopMemoryContext / :top_post END AS top_growth
FROM columnar_test_helpers.columnar_store_memory_stats();
--[ RECORD 1 ]-
-top_growth | 1
+-[ RECORD 1 ]------------------
+top_growth | 1.0206132116232119
-- before this change, max mem usage while executing inserts was 28MB and
```
This PR changes the expectation to be slightly higher, such that this
random increase in memory usage doesn't cause a flaky test.
Failing test: https://app.circleci.com/pipelines/github/citusdata/citus/26256/workflows/c0870f66-3346-4f8d-a1d3-36dfd7c98289/jobs/743028
Sometimes the columnar_memory test fails in CI with the following error:
```diff
SELECT 1.0 * TopMemoryContext / :top_post BETWEEN 0.98 AND 1.02 AS top_growth_ok
FROM columnar_test_helpers.columnar_store_memory_stats();
-[ RECORD 1 ]-+--
-top_growth_ok | t
+top_growth_ok | f
-- before this change, max mem usage while executing inserts was 28MB and
```
This is almost certainly a harmless failure that simply requires bumping
the margin a little bit. However, it's impossible to say with the
current output. I was unable to reproduce this on-demand on my local
machine or even in CI. So this changes the test to include the actual
value difference in the size of TopMemoryContext when it's outside the
expected range. Then next time it fails we at least have some
information about why.
Example of failing test: https://app.circleci.com/pipelines/github/citusdata/citus/25966/workflows/d472a57b-419a-4f33-b8bc-2e174a98d4d6/jobs/730576
Jelte Fennema
Onur Tirtir
jeff-davis