MB-52958: Remove Magma::Config::IsValueCompressed

This is now unused - as per Rohan Suri:

    "It is unused. i added it initially to do lz4 compression for
    large values on Magma side if KV hasn't already compressed it. but
    later we decided to just skip compression altogether for large
    values (in this patch:
    https://review.couchbase.org/c/magma/+/180232)"

Remove setting it in KV-Engine, in preparation for removing the member
entirely from Magma.

Change-Id: I1153c8a6060490f3e5566b702612325c6483892f
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/189915
Tested-by: Build Bot <[email protected]>
Reviewed-by: Paolo Cocchi <[email protected]>

Author: daverigby

engines/ep/src/kvstore/magma-kvstore/magma-kvstore.cc

@@ -598,7 +598,6 @@ MagmaKVStore::MagmaKVStore(MagmaKVStoreConfig& configuration)
     configuration.magmaCfg.KVStorePurgerInterval =
             configuration.getMagmaExpiryPurgerInterval();
     configuration.magmaCfg.GetSeqNum = magmakv::getSeqNum;
-    configuration.magmaCfg.IsValueCompressed = magmakv::isCompressed;
     configuration.magmaCfg.GetExpiryTime = [this](const magma::Slice& slice) {
         return getExpiryOrPurgeTime(slice);
     };