The retry mechanism in NotesBranchUtil is inflexible, and only retries a
fixed number of times on lock failure, with a fixed wait in between, up
to 250ms total. Now that we have RetryHelper available globally, make
use of that instead. This allows us to eliminate a lot of code from
NotesBranchUtil, which is a good thing, since this extra code also has
some bugs. For example, it doesn't handle all possible
RefUpdate.Results.
This is a philosophical difference in how to approach retries, which
requires fixing downstream code, including in the reviewnotes plugin.
RetryHelper is designed to be run at the highest level, completely
reopening the repository, to ensure we get the latest ref state and
start with a fresh inserter.
Since we now expect downstream plugins to use RetryHelper, export
guava-retrying from the plugin API.
Change-Id: I8a93e20f811a7c67c5cfd9cdf630afac7327c64f
36b9d3e991