This decrements the key's counter by delta. If the counter does not exist, one of two things may happen: 1. If the expiration value is all one-bits (0xffffffff), the operation

will fail with StatusNotFound.

2. For all other expiration values, the operation will succeed by

seeding the value for this key with the provided initValue to expire
with the provided expiration time. The flags will be set to zero.

NOTE: 1. If you want to set the value of the counter with add/set/replace,

the objects data must be the ascii representation of the value and
not the byte values of a 64 bit integer.

2. Decrementing a counter will never result in a "negative value" (or

cause the counter to "wrap"). instead the counter is set to 0.