Nuke some old deprecated flags

[gouthamve]

We have some deprecated flags in our code base for long and I think it's time we cleaned up some of them :)

Deleted the useless flags (they do nothing even if set):

bigtable.max-recv-msg-size
ingester.client.max-recv-message-size
ingester.client.compress-to-ingester
distributor.compress-to-ingester
ingester.search-pending-for
ingester.reject-old-samples
ingester.reject-old-samples.max-age
ingester.validation.max-length-label-name
ingester.validation.max-length-label-value
ingester.max-label-names-per-series

Other flags (use -store.index-cache-read.*):

store.index-cache-size
index.memcached.*

[bboreham]

ingester.search-pending-for was only removed a month ago.

Upon checking, I see we have two more of these in our config; silently removing options is a really bad idea and is not what "deprecated" means.

[gouthamve]

I'd like to disagree here. Having the flags set causes the operator to think that they still work when they don't. I prefer breaking things in this case so we can fix them. Case in point which drove me to do this (in our ksonnet):

-      'ingester.search-pending-for': '5m',
+      'ingester.max-transfer-retries': 60,  // Each retry is backed off by 5s, so 5mins for new ingester to come up.

Before we used to wait for 5m and now we wait less than 50s (before I made the changes above, a month after I should have).

Changing the behavior like above is a breaking change and making them explicit is much better than implicit.

[bboreham]

A warning message is better than silent.
The radical change in wait time is a bug #1307

I don't think you are disagreeing with me: I am arguing that silently ignoring options is the worst thing to do.