gui: use createspend command for coin selection and missing amount
#1729
| Job | Run time |
|---|---|
| 1m 35s | |
| 32s | |
| 3m 44s | |
| 7m 48s | |
| 5m 3s | |
| 52s | |
| 1m 22s | |
| 1m 46s | |
| 5m 46s | |
| 14m 4s | |
| 6m 58s | |
| 2m 41s | |
| 3m 59s | |
| 5m 24s | |
| 1h 1m 34s |