Remove PartyA(Shortcode) from B2B & B2C Calls

In these calls the code looks like this:

````js
const { shortCode } = mpesaApi.configs
const testMSISDN = 254708374149
await mpesaApi.b2c(shortCode, testMSISDN, 100, URL + '/b2c/timeout', URL + '/b2c/success')
````
The first argument is redundant and hence can be removed