(PDB-868) Add exponential back offs for db retry logic

This patch provides greater amount of retries, and exponential backoff logic
to avoid the case where the database is still throwing errors for a short
period of time. This commonly occurs during database restarts, and so this
logic is specifically targeted to handle smaller transient failures (not
large ones).

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #1086 from kbarber/ticket/stable/pdb-868-improve-57p01-retries

(PDB-868) Add exponential back offs for db retry logic