Remove duplicated avsc files used for datagen

These 2 tutorials have duplicate avsc files used for custom datagen. This duplication is error prone (maintaining 2 copies) and I think this duplication may be unnecessary -- the tutorial should be written to reference the same file. This GH issue tracks doing that investigation whether duplication can be eliminated.

```
sliding-windows/kstreams/code/datagen-temperature-reading.avsc
sliding-windows/kstreams/code/tutorial-steps/dev/datagen-temperature-reading.avsc

kafka-streams-schedule-operations/kstreams/code/configuration/datagen-logintime.avsc
kafka-streams-schedule-operations/kstreams/code/datagen-logintime.avsc
```

cc: @bbejeck