executeRestoreFullBackup should use context from caller to pass down to 'restoreFiles'

[rsajwani]

Description

Currently executeRestoreFullBackup calls to restoreFiles using context.Background(), this implies that it can run forever. Since executeRestoreFullBackup ignores the ctx passed to it by the caller, there is no way for restore to be cancelled once it is initiated.

This can return sucessfull restore even if there was any failure down the stack during restoreFiles.

Expectation

Context cancelled or timed-out at caller level should be respcted by restoreFiles to make sure restore returns failure incase of context cancelled or timed-out.