We have test cases for incr related commands with no key exist and
spaces in key and wrong type of key. However, we dont have test cases
covered for INCRBY INCRBYFLOAT DECRBY INCR DECR HINCRBY HINCRBYFLOAT
ZINCRBY with valid key and invalid value as argument, and float value to
incrby and decrby. So added test cases for the scenarios in incr.tcl.
Thank you!