rangefeed: attempt to resolve intents on barrier failure

[erikgrinaker]

Resolving the intents may remove the need for the barrier in the first place, reducing the impact of a persistent barrier failure.

Touches #119333.
Epic: none
Release note: None

[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is 

[erikgrinaker]

This won't do anything for ambiguous aborts, since there is no transaction record to tell us which intents to resolve.