perf(artifacts): use pageSize=1 when resolving prior artifacts (#2955)

[mattnworb]

This is a smaller-scoped attempt at
#2938, which relates to
spinnaker/spinnaker#4367.

ArtifactResolver.resolveArtifacts(Map) currently attempts to load
all executions for a pipeline in order to find the most recent
execution in the course of resolving expected artifacts. This causes a
lot of unnecessary data to be loaded from Redis/SQL, only to be
discarded a few operations later.

This change makes use of the fact that the ExecutionRepository
implementations will respect the executionCriteria.pageSize argument
when retrieving Execitions for a pipelineId.

In the Redis-based implementation, the executions are stored in a sorted
set scored on buildTime (or currentTimeMillis() if buildTime is
null), so retrieving all of the executions for the pipelineId with a
pageSize=1 should load the Execution with the most recent buildTime.

In the SQL-based implementation,
retrievePipelinesForPipelineConfigId(String, ExecutionCriteria) sorts
the query results based on the id field.

For both implementations, this is a small change from the existing
behavior of ArtifactResolver, which retrieves all executions and then
uses the one with the most recent startTime (or id). This change
seems like it will lead to the same result in most cases though, since
buildTime is set when the Execution is stored, and the id field is
ascending based on the timestamp of when it is generated.

The retrievePipelinesForPipelienConfigId method in both
implementations currently ignores the executionCriteria.sortType
field, but I've added this in the call from ArtifactResolver to at
least document ArtifactResolver's desire.

[mattnworb]

@maggieneterval @ezimanyi sorry for the noise, I hope this PR satisfies the bot 😀