Refactor ErrorInfo in ErrorPolicyManager

This change refactor the ErrorInfo into 2 different immutable subclass
for RetryIndex based and Tunnel configured back off time based,
separating the logic for better readability. Also simplified some
conditions like null checking.

Bug: 307486851
Test: atest
Change-Id: I708e186b23f0880d0fb546d94331b72262a0cc6d
4 files changed