modules: add slf4j-nop where it is missing

[xnox]

Default startup of elasticsearch results in warnings:

[WARN ][stderr ] [es] SLF4J: No SLF4J providers were found.
[WARN ][stderr ] [es] SLF4J: Defaulting to no-operation (NOP) logger implementation
[WARN ][stderr ] [es] SLF4J: See https://www.slf4j.org/codes.html#noProviders for further details.

It seems like most modules and plugins install nop logger, but some don't. If one installs them everywhere, these warnings seem to go away.

[xnox]

I think this is possibly CC @rjernst and ping to @elastic/es-core-infra (Team:Core/Infra) and is like :Core/Infra/Logging despite being a change to gradle dependencies.

[rjernst]

The warning is telling us we are hiding any messages sent to slf4j in these plugins. Adding the nop jar only makes the warning go away, but doesn't fix the problem. I think instead we want a bridge.

[xnox]

The warning is telling us we are hiding any messages sent to slf4j in these plugins. Adding the nop jar only makes the warning go away, but doesn't fix the problem. I think instead we want a bridge.

Ok!

All other plugins that include slf4j API jar, also include the nop jar already - do they also need to be changing?

[rjernst]

Yes, any plugin using slf4j should be changed.

[elasticsearchmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[fbaligand]

In order to not loose all logs that come through slf4j, it would be nice to add "log4j-slf4j-impl" dependency for each module that requires "slf4j-api" dependency.
Like "x-pack-ent-search" module does.

[DaveCTurner]

I'm closing this because it's not the approach we want. I opened #137556 in its place to record the work to be done in this area.