Fix q global concurrency

[maxdml]

• Correctly retrieve the total number of tasks executed across all workers to compute the local limit
• When doing this query, do a FOR UPDATE NO WAIT to lock the rows -- and fail early when failing to do so.
• Adjusted the test_worker_concurrency_with_n_dbos_instances test to enforce global concurrency.

Note we now ignore LockNotAvailable errors.

Nit: this PR also adds a nifty information: an application_name which can be used for debugging.

[maxdml]

Found out that GHA uses "fork", which ofc shares the parent's global variable with the child, including the DBOS global instance, which would result in a DBOS Initialized multiple times with conflicting configuration / fastapi information error in the children.