This commit adds a bitset into each shard's in-memory index, to be used to
track undeleted series ids. Currently tsi1 support is not implemented.
When new series are added to the shard, the series id is added
to the bitset. When series are deleted from the shard, the series
ids are removed from the bitset.
Becasue each shard shares the same inmem index reference, the bitset
is stored in the `ShardIndex`, which is local to each shard, and then
different references are passed into the shared `Index` object, depending
on which shard is writing the series.
This commit ensures that the series file should work appropriately on
32-bit architecturs. It does this by reducing the maximum size of a
series file to 512MB on 32-bit systems, which should be fully
addressable.
It further updates tests so that the series file size can be reduced
further when running many tests in parallel on 32-bit architectures.
Jacob Marble
Ben Johnson
Edd Robinson