apache: bump MaxClients from 40 to 100 for bits

40 is regularly being exhausted during bits deploys. It's also
unreasonably low, as a) the bits requests are cheap, b) the machines
themselves are fairly idle, b) there are just a few of bits apaches, so
even the aggregate effect won't cascade to other subsystems.

Increase this to 100, which is more of a guess than a
proven-in-benchmarks number, but which should fix outages.

Change-Id: I9e311c98fc00a4c197e62e9083398dbac66cdd85
Merge "apache: bump MaxClients from 40 to 100 for bits" into production