Set connection URI params that work

[mhutchinson]

The modernc sqlite implementation didn't use the same parameter names as the old one, and they were ignored silently. This change restores the same behaviour. I explicitly set the default value for synchronous because changing this to NORMAL means that some transactions could be dropped, which the witness can't permit without breaking its claims.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 24.83%. Comparing base (4d16f34) to head (729542a).

Files with missing lines	Patch %	Lines
cmd/omniwitness/monolith.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #562   +/-   ##
=======================================
  Coverage   24.83%   24.83%           
=======================================
  Files          27       27           
  Lines        2009     2009           
=======================================
  Hits          499      499           
  Misses       1404     1404           
  Partials      106      106           

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