Fix HOLD SCPI float formatting precision

[grasswang]

Fixed float formatting precision for the HOLD SCPI command.

The code was using %e, which truncated the value and reduced delay/holdoff precision in readback/write formatting. This changes it to %.11e so the full intended precision is preserved.

[anjohnson]

The commit log doesn't mention that it actually updates all of the SCPI commands that use %e to %.11e, not just HOLD.

[grasswang]

Thank you for pointing it out.
This modified TRIG_HOLDOFF, BURST_DELAY, and all 8 Delays.
I tested all of the modified parameters with our device. With the modification, it can now take 0.123456789123. (But the device would get 0.0123456789125 because the device's resolution is 5 ps.)