Push Database Finish Processing Tasks to context background process

[trey-ivy]

Currently, when you have a large build that takes severals seconds to save to the database, the process can fail to save if the client uses the --bes_upload_mode=fully_async flag

This flag causes the client to send a graceful shutdown upon completion of transmission w/out waiting for an acknowledgment from the server. If the database process isn't done saving before this shutdown is received, the context is destroyed and the save fails (see below)

This also causes issues when the server tries to acknowledge requests

To address this, we can push the database save to a background process and let it finish in its own time, and we can ignore send errors when the client gracefully terminated the connection. (i think...? its not like we were doing anything but logging them anyway so....).

• improve database save functionality to be more robust and store as much of an invocation as it can
• remove fk restraint on eventFile url, fix event file url formatting
• push db save to a background process
• remove caching for bazel invocations table view
• update make lint

[mortenmj]

lgtm