[FAB-10132] Align outlier peer CLI success msg log lvl

The "peer channel fetch" and "peer chaincode install" commands
currently log their success output message at the debug level.
This can make certain integration/e2e tests fail unexpectedly
if the log level is set to any other level.

It seems natural that the logged success message should be at
the info level.

Change-Id: I8ad961a5b55b7a353f329218d9090457ed1bf0be
Signed-off-by: Will Lahti <wtlahti@us.ibm.com>