R1:16a584ac7e3a

Make `bin/phd debug` quieter by default

Summary:
By default, `bin/phd debug` activates `--trace`, which is incredibly verbose.

Instead, be moderately verbose by default, and only include tracing if `--trace` was passed to `bin/phd debug`.

See also D15422.

Test Plan:
- Ran `bin/phd debug task`, got moderate amount of most useful debug output.
- Ran `bin/phd debug task --trace`, got very verbose, detailed low-level debug output.

Reviewers: chad

Reviewed By: chad

Differential Revision: https…