Backport of #54576.
This commit is part of issue #40366 to remove disabled Xlint warnings
from gradle files. Remove the Xlint exclusions from the following files:
- x-pack/plugin/rollup/build.gradle
- x-pack/plugin/monitoring/build.gradle
- x-pack/qa/rolling-upgrade-basic/build.gradle
Add type parameters to parameterized types. Add wildcard-type parameters
or bounded wildcard-type parameters. Suppress `unchecked` and `rawtypes`
warnings at method level.