DRILL-2638: Regularize startup/shutdown logging a bit in/near Drillbit.

In Drillbit:
- Added shutdown time (ms).
- Regularized to have bracketing "starting" and "finished" messages (when DEBUG
  enabled; include only messages with times at INFO level).  (See examples below.)
- Edited text.

In FunctionImplementationRegistry
- DEBUG -> INFO for message with startup time.
- Edited text.

(Examples:
At DEBUG level:

... DEBUG o.apache.drill.exec.server.Drillbit - Starting new Drillbit.
... DEBUG o.apache.drill.exec.server.Drillbit - Construction started.
... INFO  o.apache.drill.exec.server.Drillbit - Construction completed (1259 ms).
... DEBUG o.apache.drill.exec.server.Drillbit - Startup begun.
... INFO  o.apache.drill.exec.server.Drillbit - Startup completed (5359 ms).
... DEBUG o.apache.drill.exec.server.Drillbit - Started new Drillbit.
...
... DEBUG o.apache.drill.exec.server.Drillbit - Shutdown begun.
... INFO  o.apache.drill.exec.server.Drillbit - Shutdown completed (6346 ms).

At INFO level:

... INFO  o.apache.drill.exec.server.Drillbit - Construction completed (1259 ms).
... INFO  o.apache.drill.exec.server.Drillbit - Startup completed (5359 ms).
...
... INFO  o.apache.drill.exec.server.Drillbit - Shutdown completed (6346 ms).
)

0 files changed, 0 insertions, 0 deletions