Stop createTables from hanging on table locks

[sjoelund]

Jobs got stuck at 0% CPU right after fetching the reference files. On the shared PostgreSQL database every run kept the transaction of its first SELECT open until the results were written, holding a share lock on libversion, omcversion and the branch table for hours. The next run's createTables issued ALTER TABLE ... ADD COLUMN IF NOT EXISTS and CREATE INDEX IF NOT EXISTS, which take their table lock before checking whether there is anything to do, so it waited for those runs to finish - and every later reader of the table queued behind it.

• createTables only alters or indexes what is actually missing, and sets a lock_timeout so a needed lock fails the run instead of hanging it.
• test.py commits after choosing the libraries and after querying the expected execution times, so a run no longer locks the tables while testing.
• Run test.py with PYTHONUNBUFFERED: stdbuf does not affect Python, so its output lagged behind git's and a hang looked like it was in git. Also print each library before loading it.
• NeuralNetwork and URDFModelica reference files live on main; the reset to the default origin/master failed and left them stale.

Assisted-by: Claude Opus 5.5