This ensures that the docs and the metrics code
is regenerated when building the core-addon.

This guarantees Glean files get generated.

This fixes the warning (!) Plugin node-resolve: preferring built-in module 'util' over local alternative at '/home/dexter/rally-core-addon/node_modules/util/util.js', pass 'preferBuiltins: false' to disable this behavior or 'preferBuiltins: true' to disable this warning

This works around rollup/plugins#843.

See the documentation: https://github.com/rollup/plugins/tree/master/packages/node-resolve#exportconditions

Glean is disabled by default when building the core-addon.
The config-enable-glean option enables Glean. Note that,
if Glean is not initialized, no metric recording happens,
even if the Glean specific metrics APIs are called.

Unfortunately this "hack" is required because the add-ons
pipeline does not enable consumers to customize the installed
packages.

In the spirit of keeping this PR simple, this commit
removes the pings definition file.