Summary:
D38767 caused the memory usage of the PG catcache to increase slightly, causing TestToastFunction.testCatalogRefreshMemoryUsage and TestToastFunction.testAdHocMemoryUsage to fail.

This revision raises the expected memory usage to account for this.
Jira: DB-13254

Test Plan:
```
./yb_build.sh --java-test 'org.yb.pgsql.TestToastFunction'
```

Reviewers: myang

Reviewed By: myang

Differential Revision: https://phorge.dev.yugabyte.com/D38852