[Fix] Immediately clear the filter cache when requested

[ghost]

Fixes #8285

@dakrone splitting up my previous pull request #10178 as requested.

[clintongormley]

@jpountz is this change still relevant given the reworking of queries/filters in master?

[kimchy]

this fix is problematic, since it clears all the filters on the node level, not only the ones relating to a this specific index. Also, the reference to #8285 is incorrect, as its a different case of problem, its not the fact that cleanup is not called on the guava cache.

We can make IndicesFilterCache#ReaderCleaner a instance variable and explicitly call something like "forceCleanup" (synchronized) that calls the the parts of the run method (without scheduling another run) that ends up cleaning the respective parts relating to that index.

[jpountz]

@clintongormley If we move to the Lucene filter cache, this should not be necessary since it has synchronous removals.

[clintongormley]

thanks @jpountz.

thanks for the PR @Myll but I think we won't fix it as the whole mechanism is changing with Lucene 5