Automatically deduplicate "overlapping" packages

[jportner]

Describe the feature:

When upgrading packages, we often make a best effort to take the opportunity deduplicate transitive dependencies, but it's a burdensome, manual process.
It would be nice if we could automate this during yarn kbn bootstrap!

I found yarn-deduplicate that could do the trick for now. We are currently using Yarn v1.22.15. When we eventually upgrade to Yarn 2+, it supports package deduplication natively without any third party tools.

Describe a specific use case for the feature:

Sample PR where this extra effort could be avoided: #125526 (review)

I ran yarn-deduplicate locally and here is the result:

git diff --stat
 yarn.lock | 2190 ++++++++---------------------------------------------------------
 1 file changed, 266 insertions(+), 1924 deletions(-)

After rerunning yarn kbn bootstrap, my node_modules folder size went down from 2.1G to 1.8G. This could also reduce the size of our distributables!

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[jportner]

Another example why we should implement this--

I had just upgraded a dependency, and then another PR (from another team) introduced an older version of that dependency. I had to submit a third PR to fix it: #126301