Removes a deprecation warning and simplifies code.

Implements #32554.

We were using the same path for BridgeDB metrics in out/ and recent/,
and file names didn't contain the "-bridgedb-metrics" suffix that we
intended to add.

We're now using paths generated by BridgedbMetricsPersistence.

Also update create-tarballs.sh to create BridgeDB metrics tarballs.

Still part of #19332.

Implements #31204.

Implements part of #19332.

Turns out that one of the tests that we disabled earlier was only
slow, because creating a URL instance to https://something.dummy.org/
triggered an actual DNS resolve. There's absolutely no need to do
this, so we can as well use localhost in all our test URLs.

Also skip two tests in ConfigurationTest that together take 53 seconds
which has the effect that we don't run tests very often.

Implements #31599.

Implements part of #31649.

These changes still belong to archiving bridge pool assignments. But
they're not important enough for putting out a new release at this
point.

Implements #31558.

Implements #29461.

Configuration is held in the .gitlab-ci.yml file.

Fixes: #31399

Includes an upgrade to the latest metrics-base commit 256e619.

Implements part of #31326.

Implements #30219.

Turns out that updating all dependencies, including those in
metrics-web and exonerator using servlets and JSPs, is much harder
than expected. We decided to revert all these changes for now, so that
we can merge patches again. We're going to investigate alternatives
like Ant + Ivy, Maven, or Gradle in the near future.

Also include change log entries and fix a few Checkstyle complaints.

Also upgrade to latest metrics-base.

Checkstyle is excluded from this update.