Ethy NotaryKeys does not update when forced era

[surangap]

behavior

• introduce a new validator during a session
• force era
• validator goes into pending at the start of the next session/end of the current session
  • notary_keys == x
  • next_notary_keys == x + y
• at the start of the next session(S2) validator goes into the active validator list
  • but the notary_keys remain the same as above. does not update to the value of next_notary_keys

RCA
StakingSessionTracker returns the correct outputs, but if the validator becomes active at the start of the S2/ end of the S1, it would return is_active_session_final() false, which is correct. But the emergency notary keys rotation code path is within is_active_session_final scope. so it would not trigger.

notary_keys would be updated at the next natural era change

[surangap]

Code paths also confirmed on a local setup