Issue with releasing connections on updating interleaved/non-interleaved table with generated column.

We have a simple DB use case where we perform 2 operations:

1. A read operation and
2. An update operation using partitionedDML on a table with a generated column. This table is interleaved under a parent table.
On updating the table, it appears that the spanner connection is not released in time, causing a `context deadline exceeded error.`

You can find a sample working stub [here](https://github.com/GurpreetAri/UpdatePOC) with a README that explains this issue in greater detail and directions to execute the code.

The issue is intermittent but is reproducible most of the time.