NMSettingsConnection has 3 properties that are related to autoconnect:
  - autoconnect_retries
  - autoconnect_blocked_until
  - autoconnect_blocked_reason

autoconnect_blocked_reason is entirely independent from the other two.
A connection have have autoconnect blocked via a blocked-reason, but the
retry count is not affected by that. The retry count is an independent
mechanism, that may additionally prevent autoconnect.

However autoconnect_retries and autoconnect_retries_blocked_until are
strongly related. The latter is set if and only if autoconnect_retries is
at zero.

Rename to reflect that better.