[REFACTOR] Inclusion of kill switch in configs table

[prajjwalkumar17]

Description

This refactor will ensure to be presence of a kill switch(merchant-wise) for Blocklist Feature.
We will always check for a Boolean entry in configs table i.e guard_blocklist_for_{merchant_id} and all the blocklist flows(validation & fingerprint generation) will only run if the variable is set to be true.
Else if the data is not present it will take it false(as default) and blocklist flows will be disabled.

Testing steps

For testing when the blocklist flows are disabled(That are by default) :

1. Create a payment
2. Confirm it
After a successful confirm the `fingerprint` entry in the response should be null.

For testing when the blocklist flows are enabled :

1. Set/Create the entry `guard_blocklist_for_{merchant_id}` in configs table and set it to true.

After this all further testing steps can be followed from the parent issue