Increase add mining context timeout to max_timeout

[Neylix]

Description

There is some possibility due to high network latency that a coordinator node receive a start mining message after the timeout of processing the context received from cross validation nodes.
In this case the coordinator wait for the context it'll never receive and the cross validation node wait for the validation stamp they'll never receive.
The coordinator fall in timeout due to no context received and notify the welcome node of transaction failure. While the cross validation nodes elect a new coordinator node and continue the validation.

This PR fixes it by increasing the add mining context processing to the maximum time before changing the coordinator node

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules