Review all latestDepTestLibrary versions that have an upper limit

[trask]

latestDepTestLibrary implicitly uses the latest version available in maven central, e.g.

But sometimes we have to apply an upper limit for one reason or another.

E.g.

latestDepTestLibrary group: 'org.elasticsearch.client', name: 'transport', version: '5.+'

where the upper limit is needed because we have separate instrumentation for 6.0.

And

latestDepTestLibrary group: 'io.lettuce', name: 'lettuce-core', version: '5.+'

where the upper limit is needed in order to avoid an alpha version 6.0.0.M1.

And sometimes the upper limit is needed because we haven't fixed the tests or the instrumentation to run on the latest version.

It would be good to review all of these upper limits, and try to categorize these upper limits:

• Upper limit due to multi-versioned instrumentation
• Upper limit due to latest version being alpha (and don't want to deal with alpha API churn)
• Upper limit that should to be lifted

and decide on a plan for how to manage these going forward so the upper limit are not forgotten about.